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THE  SEARCHER 


.  U>4;  :  ... 

Ottr-AHTMENT  OF  CIVIL.  EH^^SN.^kf^^ 
BERKELEY.  CAUIFORNIM 


5j„,vE«smr  or  ct-iw*^ 
r^fmr^fsr^  OF  civn-  en^ik^^^^ 

BERKELEY.  CAUITORNIft 


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EINSTEIN   THE   SEARCHER 


EINSTEIN 
THE  SEARCHER 

HIS    WORK    EXPLAINED    FROM 
DIALOGUES  WITH  EINSTEIN 


BY  '••.:;:; 

ALEXANDER  MOSZKOWSkt 


TRANSLATED   BY 

HENRY    L.    BROSE 


r 


NEW   YORK 
P.    BUTTON   AND   COMPANY 
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EXTRACT  FROM  THE  AUTHOR'S 
PREFACE 

THE  book  which  is  herewith  presented  to  the  public 
has  few  contemporaries  of  a  Uke  nature ;  it  deserves 
special  attention  inasmuch  as  it  is  illuminated  by  the 
name  Albert  Einstein,  and  deals  with  a  personality  whose 
achievements  mark  a  turning-point  in  the  development  of 
science. 

Every  investigator,  who  enlarges  our  vision  by  some 
permanent  discovery,  becomes  a  milestone  on  the  road  to 
knowledge,  and  great  would  be  the  array  of  those  who  have 
defined  the  stages  of  the  long  avenue  of  research.  One  might 
endeavour,  then,  to  decide  to  whom  mankind  owes  the  greater 
debt,  to  EucHd  or  to  Archimedes,  to  Plato  or  to  Aristotle,  to 
Descartes  or  to  Pascal,  to  Lagrange  or  to  Gauss,  to  Kepler 
or  to  Copernicus.  One  would  have  to  investigate — as  far  as 
this  is  possible — in  how  far  each  outstanding  personaUty  was 
in  advance  of  his  time,  whether  some  contemporary  might 
not  have  had  the  equal  good  fortune  to  stumble  on  the  same 
discovery,  and  whether,  indeed,  the  time  had  not  come  when 
it  must  inevitably  have  been  revealed.  If  we  then  further 
selected  only  those  who  saw  far  beyond  their  own  age  into  the 
iUimitable  future  of  knowledge,  this  great  number  of  celebrities 
would  be  considerably  diminished.  We  should  glance  away 
from  the  milestones,  and  fix  our  gaze  on  the  larger  signs  that 
denote  the  lines  of  demarcation  of  the  sciences,  and  among 
them  we  should  find  the  name  of  Albert  Einstein.  We  may 
find  it  necessary  to  proceed  to  a  still  more  rigorous  classifica- 


68^232 


vi  EINSTEIN  THE  SEARCHER 

tion ;  Science,  herself,  may  rearrange  her  chronological  table 
later,  and  reckon  the  time  at  which  Einstein's  doctrine  first 
appeared  as  the  beginning  of  an  important  era. 

This  would  in  itself  justify— nay,  render  imperative — the 
writing  of  a  book  about  Einstein.  But  this  need  has  already 
been  satisfied  on  several  occasions,  and  there  is  even  now  a 
considerable  amount  of  hterature  about  him.  At  the  end  of 
this  generation  we  shall  possess  a  voluminous  library  com- 
posed entirely  of  books  about  Einstein.  The  present  book 
will  differ  from  most  of  these,  in  that  Einstein  here  occurs  not 
only  objectively  but  also  subjectively.  We  shall,  of  course, 
speak  of  him  here  too,  but  we  shall  also  hear  him  speak  him- 
self, and  there  can  be  no  doubt  that  all  who  are  devoted  to  the 
world  thought  can  but  gain  by  listening  to  him. 

The  title  agrees  with  the  circumstance  to  which  this  book 
owes  its  birth.  And  in  undertaking  to  address  itself  to  the 
circle  of  readers  as  to  an  audience,  it  promises  much  eloquence 
that  came  from  Einstein's  own  lips,  during  hours  of  social 
intercourse,  far  removed  from  academic  purposes  and  not 
based  on  any  definite  scheme  intended  for  instruction.  It 
will,  therefore,  be  neither  a  course  of  lectures  nor  anything 
similar  aiming  at  a  systematic  order  and  development.  Nor  is 
it  a  mere  phonographic  record,  for  this  is  made  impossible  if 
for  no  other  reason  than  that  whoever  has  the  good  fortune  to 
converse  with  this  man,  finds  every  minute  far  too  precious 
to  waste  it  in  snatching  moments  to  take  shorthand  notes. 
What  he  has  heard  and  discussed  crystallizes  itself  in  sub- 
sequent notes,  and  to  some  extent  he  relies  on  his  memory, 
which  would  have  to  be  extraordinarily  lax  if  it  managed  to 
forget  the  essentials  of  such  conversations. 

But  these  essentials  could  not  be  attained  by  cHnging 
closely  to  the  exact  terms  of  utterance.  This  would  be  a  gain 
neither  for  the  scheme  of  the  book  nor  for  the  reader  who 
wishes  to  follow  a  great  thinker  in  all  the  ramifications  of  his 
ideas.     It  must  be  reiterated  that  this  book  is  intended  neither 


EXTRACT  FROM  THE  AUTHOR'S  PREFACE  vii 

as  a  textbook  nor  as  a  guide  leading  to  a  complete  system  of 
thought ;  nor,  above  all,  is  it  in  any  way  due  to  Einstein,  nor 
desired  by  him.  Any  value  and  attraction  of  the  book  is 
rather  to  be  sought  in  its  kaleidoscopic  nature,  its  loose  con- 
nexion, which  expresses  a  general  meaning  without  being 
narrowed  to  pedantic  hmits  by  a  restriction  to  Hteral  re- 
petition. It  is  just  this  absence  of  the  method  that  is  rightly 
demanded  of  a  textbook,  which  may  enable  these  conversa- 
tions to  pass  on  to  the  world  a  httle  of  the  pleasure  which  they 
originally  gave  me.  Perhaps  they  will  even  be  sufficient  to 
furnish  the  reader  with  a  picture  of  the  eminent  scientist, 
sufficient  to  give  him  a  ghmpse  of  his  personaUty,  without 
demanding  a  detailed  study  to  secure  this  end.  Even  here 
I  should  Uke  to  state  that  the  range  of  Einstein's  genius 
extends  much  further  than  is  generally  surmised  by  those  who 
have  busied  themselves  only  with  the  actual  physical  theory. 
It  sends  out  rays  in  all  directions,  and  brings  into  view 
wonderful  cosmic  features  under  his  stimulus — features  which 
are,  of  course,  embedded  in  the  very  refractory  mathematical 
shell  of  his  physics  which  embraces  the  whole  world.  But 
only  minds  of  the  distant  future,  perhaps,  will  be  in  a  position 
to  realize  that  all  our  mental  knowledge  is  illuminated  by  the 
light  of  his  doctrine. 

Einstein's  mission  is  that  of  a  king  who  is  pursuing  build- 
ing operations  on  a  large  scale  ;  carters  and  workmen,  each 
in  their  own  line,  receive  employment  for  decades  ahead. 
But  apart  from  the  technical  work,  there  may  still  be  room 
for  non-technical  account,  which,  without  following  a  definite 
programme,  yet  pursues  a  definite  object,  to  offer  Einsteiniana 
in  an  easily  intelligible  and  ever-changing  form,  to  represent 
him,  as  it  were,  wandering  over  fields  and  meadows,  and  every 
now  and  then  stooping  to  pluck  some  problem  in  the  guise  of  a 
flower.  Seeing  that  he  granted  me  the  pleasure  of  accompany- 
ing him  on  these  excursions,  it  was  not  within  my  sphere  to 
expect  in  addition  that  he  would  direct  his  steps  according  to 


viii  EINSTEIN  THE  SEARCHER 

a  preconceived  plan.  Often  enough  the  goal  vanished,  and 
there  remained  nothing  but  the  pleasure  of  the  rambles  them- 
selves with  the  consciousness  of  their  purpose.  As  Schopen- 
hauer remarks,  one  who  walks  for  leisure  can  never  be  said  to 
be  making  detours ;  and  this  holds  true  independently  of  the 
nature  of  the  country  that  happens  to  be  traversed  at  the 
moment.  If  I  just  now  mentioned  walks  on  meadowy  slopes, 
this  is  not  to  be  understood  literally.  In  Einstein's  company 
one  encounters  from  moment  to  moment  quite  suddenly  some 
adventure  which  destroys  our  comparison  with  idylUc  rambles. 
Abysmal  depths  appear,  and  one  has  to  pass  along  dangerous 
pathways.  It  is  at  these  moments  that  unexpected  views 
present  themselves,  and  many  strips  of  landscape  that,  accord- 
ing to  our  previous  estimate,  appeared  to  be  situated  on  higher 
slopes,  are  now  discovered  reposing  far  below.  We  are 
familiar  with  the  '*  Wanderer  Fantasie  "  of  Schubert ;  its  tonal 
disposition  is  reahstic,  conforming  to  Nature,  yet  its  general 
expression  is  transcendental :  so  is  a  ramble  with  Einstein ; 
he  remains  firmly  implanted  in  reality,  but  the  distant  views 
that  he  points  out  stretch  into  transcendental  regions.  He 
seems  to  me  to  be  essentially  as  much  an  artist  as  a  discoverer, 
and  if  some  sense  of  this  heaven-sent  combination  of  gifts 
should  be  inspired  by  this  book,  it  alone  would  justify  the 
publication  of  these  talks.  ^ 


TRANSLATOR'S    NOTE 

IT  is  scarcely  necessary  to  enlarge  on  the  scope  and  design 
of  the  present  book,  which  manifest  themselves  at  a 
glance. 

The  author  merits  our  thanks  for  making  accessible  to  us 
material  about  Einstein  which,  in  the  ordinary  course  of  events, 
would  ever  remain  unknown.  An  account  of  Einstein's  work 
would  be  incomplete  without  a  sketch  of  his  personaHty. 
Mr.  Moszkowski  invites  us  to  ramble  with  Einstein  into  realms 
not  confined  to  pure  physics.  Many  subjects  that  have  a 
pecuHar  interest  at  the  present  critical  stage  of  the  world's 
history  receive  illuminating  attention.  It  is  hoped  that  the 
appearance  of  the  book  in  Enghsh  will  stimulate  further 
interest  in  the  thought- world  of  a  great  scientist. 

Warm  thanks  are  due  to  Mr.  Raymond  Kershaw,  B.A., 

and  to  my  sister.  Miss  Hilda  Brose,  for  help  in  reading  the 

manuscript  and  the  proofs. 

HENRY  L.  BROSE 

Oxford,  1921 


V 


CONTENTS 


CHAP. 

I.  Phenomena  in  the  Heavens 
II.  Beyond  our  Power 

III.  Valhalla  . 

IV.  Education 
V.  The  Discoverer 

VI.  Of  Different  Worlds 
VII.  Problems  . 
VIII.  Highways  and  By-ways 
IX.  An  Experimental  Analogy 
X.  Disconnected  Suggestions 
XI.  Einstein's  Life  and  Personality 
Index         .... 


FAGB 

I 

20 
38 
62 

88 
115 
143 
172 
192 
200 
220 
245 


2  EINSTEIN  THE  SEARCHER 

critical,  nay  epochal,  point  marking  the  commencement  of  a 
new  era  of  thought. 

*'  Perhaps  "  was  a  word  he  never  failed  to  emphasize. 
He  persistently  laid  stress  on  his  doubts,  differentiated  between 
hardened  facts  and  hypotheses,  still  clinging  to  the  hope  that 
the  new  doctrine  he  was  expounding  would  yet  admit  of  an 
avenue  leading  back  to  the  older  views.  This  revolution,  so 
he  said,  seemed  to  threaten  things  in  science  which  a  short 
while  ago  werig  looked  upon  as  absolutely  certain,  namely, 
fundamental  theorems  of  classical  mechanics,  for  which  we 
are  indebted  to  the  genius  of  Newton.  For  the  present  this 
revolution  is  of  course  only  a  threatening  spectre,  for  it  is 
quite  possible  that,  sooner  or  later,  the  old  established 
dynamical  principles  of  Newton  will  emerge  victoriously. 
Later  in  the  course  of  his  lecture  he  declared  repeatedly  that 
he  felt  a  diffidence  akin  to  fear  at  the  sight  of  the  accumulating 
number  of  hypotheses,  and  that  it  seemed  to  border  on  the 
impossible  to  attempt  to  arrange  them  into  a  system. 

It  is  a  matter  of  complete  indifference  how  the  revelations 
of  Poincar^  affected  us  individually  ;  if  I  may  infer  from  my 
own  case,  there  is  only  one  word  to  express  it — staggering ! 
Oblivious  of  the  doubts  of  the  lecturer,  I  was  swept  along  under 
the  impetus  of  this  new  and  mighty  current  of  thought.  This 
awakened  two  wishes  in  me  :  to  become  acquainted  with 
Einstein's  researches  as  far  as  lay  within  my  power,  and,  if 
possible,  to  see  him  once  in  person.  In  me  the  abstract  had 
become  inseparable  from  the  concrete  personal  element. 
The  presentiment  of  the  happy  moment  in  the  future  hovered 
before  my  vision,  whispering  that  I  should  hear  his  doctrine 
from  his  own  Ups. 

Several  years  later  Einstein  was  appointed  professor  of 
the  Academy  of  Sciences  with  the  right  of  lecturing  at  the 
University  of  Berlin.  This  brought  my  personal  wish  within 
reach.  Trusting  to  good  fortune,  I  set  about  materializing  it. 
In  conjunction  with  a  colleague  I  wrote  him  a  letter  asking 
him  to  honour  with  his  presence  one  of  the  informal  evenings 
instituted  by  our  Literary  Society  at  the  Hotel  Bristol.  Here 
he  was  my  neighbour  at  table,  and  chatted  with  me  for  some 
hours.  Nowadays  his  appearance  is  known  to  every  one 
through  the  innumerable  photos  which  have  appeared  in  the 


PHENOMENA  IN  THE  HEAVENS  0 

papers.  At  that  time  I  had  never  seen  his  countenance  before, 
and  I  became  absorbed  in  studying  his  features,  which  struck 
me  as  being  those  of  a  kindly,  artistically  inclined,  being,  in 
nowise  suggesting  a  professor.  He  seemed  vivacious  and  im- 
restrained  in  conversation,  and,  in  response  to  our  request, 
willingly  touched  upon  his  own  subject  as  far  as  the  place  and 
occasion  allowed,  exemplifying  Horace's  saying,  "  Omne  tulit 
punctum,  qui  miscuit  utile  dulci,  tironem  delect ando  pari- 
terque  monendo."  It  was  certainly  most  deHghtful.  Yet  at 
moments  I  was  reminded  of  a  male  sphinx,  suggested  by  his 
highly  expressive  enigmatic  forehead.  Even  now,  after  a 
warm  acquaintanceship  stretching  over  years,  I  cannot  shake 
off  this  impression.  It  often  overcomes  me  in  the  midst  of  a 
pleasant  conversation  interspersed  with  jests  whilst  enjoying 
a  cigar  after  tea ;  I  suddenly  feel  the  mysterious  sway  of  a 
subtle  intellect  which  captivates  and  yet  baffles  the  mind. 

At  that  time,  early  in  1916,  only  a  few  members  of  the 
Literary  Society  divined  who  it  was  that  was  enjoying  their 
hospitality.  In  the  eyes  of  Berlin,  Einstein's  star  was  be- 
ginning its  upward  course,  but  was  still  too  near  the  horizon  to 
be  visible  generally.  My  own  vision,  sharpened  by  the  French 
lecture  and  by  a  friend  who  was  a  physicist,  anticipated  events, 
and  already  saw  Einstein's  star  at  its  zenith,  although  I  was 
not  even  aware  at  that  time  that  Poincar^  had  in  the  mean- 
time overcome  his  doubts  and  had  fully  recognized  the 
lasting  importance  of  Einstein's  researches.  I  had  the 
instinctive  feeling  that  I  was  sitting  next  to  a  Galilei.  The 
fanfares  sounded  in  the  following  years  as  a  sign  of  apprecia- 
tion by  his  contemporaries  were  only  a  fuller  instriunentation 
of  the  music  of  destiny  which  had  vibrated  in  my  ears  ever 
since  that  time. 

I  recollect  one  little  incident  :  one  of  these  lovers  of 
literature,  who  was,  however,  totally  ignorant  of  natural 
science,  had  accidentally  seen  several  learned  articles  deahng 
with  Einstein's  Reports  for  the  Academy,  and  had  preserved 
the  cuttings  in  his  pocket-book.  He  considered  this  a  fitting 
opportunity  for  enhghtenment.  Surely  a  brief  question 
would  suffice  to  guide  one  through  these  intricate  channels. 
"  Professor,  will  you  kindly  tell  me  the  meaning  of  potential, 
invariant,    contravariant,    energy-tensor,    scalar,    relativity- 


4  EINSTEIN  THE  SEARCHER 

postulate,  hyper-Euclidean,  and  inertial  system  ?  Can  you 
explain  them  to  me  in  a  few  words  ?  " — "  Certainly,"  said 
Einstein,  "  those  are  merely  technical  expressions  !  "  That 
was  the  end  of  the  little  lesson. 

Far  into  the  night  three  of  us  sat  in  a  cafe  while  Einstein 
gently  lifted  the  veil  from  his  newest  discovery  for  the  benefit 
of  my  journalist  friend  and  myself.  We  gathered  from  his 
remarks  that  a  Special  Theory  of  Relativity  formed  a  prelude 
to  a  general  theory  which  embraced  the  problem  of  gravita- 
tion in  its  widest  sense,  and  hence  also  the  physical  constitu- 
tion of  the  world.  What  interested  me  apart  from  this  theme, 
which  was,  of  course,  only  touched  upon  lightly,  was  the 
personal  question  in  its  psychological  aspect. 

"  Professor,**  said  I,  "  such  investigations  must  involve 
enormous  mental  excitement.  I  imagine  that  there  lurks 
behind  every  solved  problem  ever  and  again  some  new  problem 
with  a  threatening  or  a  fascinating  aspect,  as  the  case  may  be, 
each  one  calhng  up  a  tumult  of  emotion  in  its  author.  How 
do  you  succeed  in  mastering  this  difficulty  ?  Are  you  not 
continually  tormented  by  restless  thoughts  that  noisily  invade 
your  dreams  ?  Do  you  ever  succeed  at  all  in  enjoying  undis- 
turbed slumber  ?  ** 

The  very  tone  in  which  the  answer  was  given  showed 
clearly  how  free  he  felt  himself  of  such  nervous  troubles  which 
usually  oppress  even  the  mediocre  thinker.  It  is  fortunate  that 
such  affections  do  not  penetrate  to  his  high  level.  "  I  break 
off  whenever  I  wish,"  he  said,  "  and  banish  all  difficulties  when 
the  hour  for  sleep  arrives.  Thinking  during  dreams,  as  in  the 
case  of  artists,  such  as  poets  and  composers,  by  which  they 
weave  the  thread  of  day  on  into  the  night,  is  quite  foreign  to  me. 
Nevertheless,  I  must  confess  that  at  the  very  beginning,  when 
the  special  theory  of  relativity  began  to  germinate  in  me,  I  was 
visited  by  all  sorts  of  nervous  confficts.  When  young  I  used 
to  go  away  for  weeks  in  a  state  of  confusion,  as  one  who  at  that 
time  had  yet  to  overcome  the  stage  of  stupefaction  in  his  first 
encounter  with  such  questions.  Things  have  changed  since 
then,  and  I  can  assure  you  that  there  is  no  need  to  worry  about 
my  rest." 

**  Notwithstanding,"  I  answered,  "  cases  may  arise  in 
which  a  certain  result  is  to  be  verified  by  observation  and 


PHENOMENA  IN  THE  HEAVENS  5 

experiment.  This  might  easily  give  rise  to  nerve-racking 
experiences.  If,  for  instance,  a  theory  leads  to  a  calculation 
which  does  not  agree  with  reality,  the  propounder  must  surely 
feel  considerably  oppressed  by  this  mere  possibility.  Let  us 
take  a  particular  event.  I  have  heard  that  you  have  made  a 
new  calculation  of  the  path  of  the  planet  Mercury  on  the 
basis  of  your  doctrine.  This  must  certainly  have  been  a 
laborious  and  involved  piece  of  work.  You  were  firmly  con- 
vinced of  the  theory,  perhaps  you  alone.  It  had  not  yet  been 
verified  by  an  actual  fact.  In  such  cases  conditions  of  great 
psychological  tension  must  surely  assert  themselves.  What  in 
Heaven's  name  will  happen  if  the  expected  result  does  not 
appear  ?  What  if  it  contradicts  the  theory  ?  The  effect  on 
the  founder  of  the  theory  cannot  even  be  imagined  !  " 

"  Such  questions,"  said  Einstein,  "  did  not  he  in  my  path. 
That  result  could  not  be  otherwise  than  right.  I  was  only 
concerned  in  putting  the  result  into  a  lucid  form.  I  did  not 
for  one  second  doubt  that  it  would  agree  with  observation. 
There  was  no  sense  in  getting  excited  about  what  was  self- 
evident." 

Let  us  now  consider  several  facts  of  natural  science,  apart 
from  this  chat,  but  suggested  by  it,  which  caused  Einstein  Uttle 
excitement,  but  the  whole  world  generally,  so  much  the  more. 
By  way  of  illustration  we  shall  Hnk  them  up  with  the  result  of 
a  forerunner  who,  Hke  Einstein,  fixed  on  paper  what  should 
happen  in  the  heavens. 

Formerly,  whenever  one  wished  to  play  a  particularly 
effective  trump  card  in  favour  of  research  work  it  was  cus- 
tomary to  quote  the  achievement  of  the  French  astronomer 
Leverrier  who,  pen  in  hand,  estabhshed  the  material  existence 
of  a  planet  at  that  time  quite  unknown  and  unnoticed.  Certain 
disturbances  in  the  orbit  of  the  planet  Uranus,  which  was 
regarded  as  being  the  most  distant  of  the  wandering  stars,  at 
that  time  had  caused  him  to  beUeve  in  the  certainty  of  the 
existence  of  a  still  more  distant  planet,  and  by  using  merely 
the  theoretical  methods  of  celestial  mechanics  in  connexion 
with  the  problem  of  three  bodies  he  succeeded  in  revealing 
what  was  hidden  behind  the  visible  constellations.  He  reported 
the  result  of  his  calculations  to  the  BerUn  Observatory  about 
seventy-five  years  ago,  as  it  was  at  that  time  in  possession  of 


6  EINSTEIN  THE  SEARCHER 

the  best  instruments.  It  was  then  that  the  amazing  event 
happened  :  on  the  very  same  evening  an  observer  in  Berlin, 
Gottfried  Galle,  discovered  the  predicted  new  star  almost 
exactly  at  the  point  of  the  heavens  for  which  it  was  prophesied, 
only  half  the  moon's  diameter  from  it.  The  new  planet 
Neptune,  the  farthest  outpost  of  our  solar  system,  reposed  as 
a  prisoner  in  his  telescope  ;  the  seemingly  undiscoverable  star 
had  capitulated  in  the  face  of  mental  efforts  of  a  mathematical 
scholar,  who,  in  reasoning  meditation,  had  sketched  his  curves 
in  the  quiet  atmosphere  of  his  study. 

This  was  certadnly  bewildering  enough,  but  nevertheless 
this  incredible  result  which  stirred  the  imagination  so  strongly 
was  directly  rooted  in  reality,  lay  on  the  path  of  research, 
followed  of  necessity  from  the  laws  of  motion  known  at  that 
time,  and  disclosed  itself  as  a  new  proof  of  the  doctrines  of 
astronomy  which  had  long  been  recognized  as  supreme  and 
incontestable.  Leverrier  had  not  created  these,  but  had  found 
them  ready  ;  he  appHed  them  with  the  mind  of  genius.  Any- 
one who  nowadays  is  sufficiently  trained  to  work  through  the 
highly  complicated  calculation  of  Leverrier  has  every  reason 
to  marvel  at  a  work  which  is  entirely  mathematical  throughout. 
Our  own  times  have  been  marked  by  an  event  of  still  greater 
significance. 

Irregularities  had  shown  themselves  in  observation  of  the 
heavens  that  could   not    be    explained   or   grasped    by  the 
accepted  methods  of  classical  mechanics.     To  interpret  them, 
ideas  of  a  revolutionary  nature  were  necessary.     Man's  view  of 
the  plan  according  to  which  the  universe  is  mapped  out  had 
to  be  radically  reformed  to  bring  within  comprehension  the 
problems  that  presented  themselves  in  macroscopic  as  well  as 
in  microscopic  regions,  in  the  courses  of  the  stars  as  well  as  in 
the  motions  of  the  ultimate  constituents  of  the  atom  of  material 
bodies,  incapable  of  being  directly  observed.     The  goal  con- 
sisted in  bringing  those  doctrines  in  which  truth  had  been 
proclaimed  in  its  essential  features,  but  not  exhaustively,  by 
the  genius  of  Copernicus,  GaHlei,  Kepler,  and  Newton,  to  their 
conclusion  by  penetrating  as  far  as  possible  into  the  mysteries  of 
the  structure  of  the  universe.     This  is  where  Einstein  comes 
forward. 

Whereas  the  outermost  planet  Neptune  had  bowed  to  the 


PHENOMENA  IN  THE  HEAVENS  7 

accepted  laws,  by  merely  disclosing  his  presence.  Mercury,  the 
innermost  planet,  preserved  an  obstinate  attitude  even  in  the 
face  of  the  most  refined  calculations.  These  always  led  to 
an  imaccountable  remainder,  a  disagreement,  which  seemed 
very  small  when  expressed  in  numbers  and  words,  and  yet 
enclosed  a  deep  secret.  Wherein  did  this  disagreement 
consist  ?  In  a  difference  of  arc  which  had  Hkewise  been  dis- 
covered by  Leverrier  and  which  defied  explanation.  It  was 
only  a  matter  of  about  forty-five  insignificant  quantities, 
seconds  of  arc,  which  seemed  vanishingly  small  since  this 
deviation  did  not  occur  within  a  month  or  a  year,  but  was 
spread  over  a  whole  century.  By  just  so  much,  or  rather  so 
little,  the  rotation  of  Mercury's  orbit  differed  from  what  might 
be  termed  the  allowable  astronomical  value.  Observation  was 
exact,  calculation  was  exact ;  why,  then,  the  discrepancy  ? 

It  was  thus  inferred  that  there  was  still  some  hidden  un- 
explored factor  which  had  to  be  taken  into  account  in  the 
fundamental  principles  of  celestial  mechanics.  The  formerly 
invisible  Neptune  confirmed  the  old  rule  by  appearing. 
Mercury,  which  was  visible,  opposed  the  rule. 

In  1 9 10  Poincar^  had  touched  upon  this  embarrassing 
question,  mentioning  that  here  was  a  possibility  of  testing 
the  new  mechanics. 

He  decHned  the  suggestion  of  some  astronomers  that  this 
was  again  a  Leverrier  problem  and  that  there  must  exist  another 
undiscovered  planet  still  nearer  the  sim  and  disturbing 
Mercury's  orbit.  He  also  refused  to  accept  the  assumption 
that  the  disturbance  might  be  caused  by  a  ring  of  cosmic 
matter  distributed  round  the  sun.  Poincar^  divined  that  the 
new  mechanics  could  supply  the  key  to  the  enigma,  but, 
obviously  to  be  quite  conscientious,  he  expressed  his  presenti- 
ment in  very  cautious  terms.  On  that  occasion  he  said  that 
some  special  cause  had  yet  to  be  found  to  explain  the  anomaly 
of  Mercury's  behaviour ;  till  that  was  discovered  one  could 
only  say  that  the  new  doctrine  could  not  be  regarded  as  in 
contradiction  to  astronomical  facts.  But  the  true  explanation 
was  gradually  drawing  near.  Five  years  later,  on  i8th  Nov- 
ember 1915,  Albert  Einstein  presented  to  the  Prussian  Academy 
of  Sciences  a  paper  which  solved  this  riddle  which,  expressed  in 
seconds,  seemed  so  insignificant  and  yet  was  of  such  enormous 


8  EINSTEIN  THE  SEARCHER 

importance  in  its  bearing  on  fundamental  questions.  He 
proved  the  problem  was  solved  quite  accurately  if  the  general 
Theory  of  Relativity  he  had  founded  was  accepted  as  the  only 
valid  basis  for  the  phenomena  of  cosmic  motions. 

Many  would  at  this  point  express  a  wish  to  have  the 
essence  of  the  doctrine  of  relativity  explained  in  an  easily 
intelligible  manner.  Indeed,  some  would  go  even  further  in 
their  desire,  and  would  ask  for  a  simple  description  in  a  few 
succinct  sentences.  This,  measured  in  terms  of  difficulty  and 
possibiUty,  would  be  about  equivalent  to  wishing  to  learn  the 
history  of  the  world  by  reading  several  quarto  pages  of  manu- 
script or  a  novelette.  But  even  if  we  start  at  long  range  and 
use  elaborate  materials  for  our  description,  we  should  have  to 
give  up  the  idea  that  this  knowledge  may  be  gained  with 
playful  ease.  For  this  doctrine,  inasmuch  as  it  discloses  the 
relationship  between  mathematical  and  physical  events, 
emerges  out  of  mathematics,  which  thus  limits  the  mode  of  its 
representation.  Whoever  undertakes  to  present  it  in  a  form 
in  which  it  is  easily  intelhgible,  that  is  quite  unmathematical 
and  yet  complete,  is  engaged  in  an  impossible  venture ;  he  is 
like  one  who  would  whistle  Kepler's  Laws  on  the  flute  or  would 
elucidate  Kant's  Critique  of  Pure  Reason  by  means  of  coloured 
illustrations.  In  all  frankness  we  must  confess  once  and  for 
all  that  whenever  popular  accounts  are  attempted  they  can  be 
only  in  the  nature  of  vague  suggestions  removed  from  the 
domain  of  mathematics.  But  even  such  indications  have  a 
fruitful  result  if  they  succeed  in  focusing  the  attention  of  the 
reader  or  the  hearer  so  that  the  connexions,  the  Leitmotivs, 
so  to  speak,  of  the  doctrine,  are  at  least  suggested. 

It  must  therefore  suffice  if  we  place  the  conception  of 
approximation  in  the  foreground  here  as  in  other  parts  of 
this  book.  Till  quite  recently  Newton's  Equations  of  Motion 
were  used  as  a  foundation  for  verifying  astronomical  occur- 
rences. These  are  symbolical  representations  expressed  as 
formulae  that  contain  in  an  exceedingly  simple  form  the  law 
of  mass  attraction.  They  express  the  comprehensive  principle 
that  the  attraction  is  directly  proportional  to  the  mass  and 
inversely  proportional  to  the  square  of  the  distance  ;  so  that 
the  moving  force  is  doubled  when  the  mass  is  doubled,  whereas 
if  the  distance  is  double,  the  force  is  only  a  quarter  as  great, 


PHENOMENA  IN  THE  HEAVENS  9 

if  the  distance  is  trebled,  the  force  becomes  one-ninth  as 
greaX. 

According  to  the  Theory  of  Relativity  this  fimdamental 
law  is  not  wrong  or  invahd,  but  no  longer  holds  fully  if  pursued 
to  its  last  inferences.  In  applying  corrections  to  it,  new 
factors  occur,  such  as  the  ratio  of  given  velocities  to  the 
velocity  of  Ught,  and  the  new  geometry  which  operates  with 
"  world-lines  "  in  space  which,  amalgamated  with  the  dimen- 
sion of  time,  is  regarded  as  a  quadruply  extended  continuum. 
Einstein  has  actually  supplemented  these  fundamental 
equations  for  the  motion  of  masses  so  that  the  original  form 
states  the  true  condition  of  affairs  only  approximately,  where- 
as Einstein's  equations  give  the  motion  with  very  great 
accuracy. 

The  above-mentioned  essay  of  Einstein  is  carried  out  as 
if  the  structure  bequeathed  to  us  by  Newton  required  the 
addition  of  a  final,  very  deHcate  pinnacle.  For  the  mathe- 
matician this  pinnacle  is  given  as  a  combination  of  signs, 
representing  a  so-called  "  EUiptic  Interval."  Such  an  in- 
terval is  a  very  weird  construction,  and  the  man  who  will 
make  it  apprehended  by  the  general  reader  is  yet  to  be  bom. 
When  Lord  Byron  said  : 

"  And  Coleridge,  too,  has  lately  taken  wing. 
But  like  a  hawk  encumbered  with  his  hood, — 
Explaining  Metaphysics  to  the  nation — 
I  wish  he  would  explain  his  Explanation." 

{Dedication  to  "Don  Juan.") 

he  had  still  a  sure  footing  in  inteUigibihty,  compared  with 
the  non-mathematician,  who  demands  an  explanation  for 
such  a  construction.  And  what  a  complex  of  mathematical 
dangers  must  be  overcome  even  before  the  question  of  the 
meaning  of  this  integral  is  crystalhzed  out ! 

But  now  the  explanation  had  arrived  and  could  be  evalu- 
ated, if  only  approximately.  Before  we  give  the  result,  let 
us  just  describe  at  least  one  technical  term,  namely,  "  Peri- 
heUon."  It  is  that  point  of  a  planetory  orbit  which  hes 
nearest  the  sun.  This  orbit  is  an  elUpse,  that  is,  an  elongated 
curved  Hne  in  the  interior  of  which  one  distinguishes  a  major 
axis  in  the  direction  of  elongation,  and  a  minor  axis  perpen- 
dicular to  the  former  at  its  middle  point.    The  periheUon 


10  EINSTEIN  THE  SEARCHER 

of  a  planetory  orbit  is  at  one  of  the  end  points  of  the  major 
axis. 

In  time  the  perihehon  alters  its  position  in  space,  ad- 
vancing in  the  same  sense  as  the  orbit  is  traversed.  Ic  would 
naturally  be  assumed  that  the  amount  of  this  advance  as 
measured  astronomically  would  agree  with  the  calculation 
resulting  from  Newton's  theory.  But  this  was  not  the  case. 
An  unaccountable  remainder  was  left  over,  which  astronomers 
ascertained  to  be  45  seconds  (of  arc)  per  100  years,  with  a 
possible  fluctuation  of  plus  or  minus  5  seconds.  Thus,  if  the 
new  result  were  found  to  lie  between  40  and  50  seconds,  the 
new  theory  would  henceforth  have  to  be  regarded  as  the  only 
valid  one. 

It  happened  just  as  Einstein  predicted  :  calculation  accord- 
ing to  his  theory  shows  that  for  the  planet  Mercury  the  peri- 
hehon should  advance  43  seconds  per  100  years.  This 
signifies  full  agreement  with  observation  and  fully  removes 
the  former  apparent  difficulty.  Whereas  Leverrier  in  his 
time  had  pointed  out  a  new  planet,  Einstein  brought  to  view 
something  far  more  important :  a  new  truth. 

It  was  a  test  of  accuracy  so  dazzHng  that  it  alone  would 
have  sufi&ced  to  prove  the  correctness  of  Einstein's  Principles. 
Yet,  a  second  test,  fraught  with  graver  and  more  far-reaching 
consequences,  presented  itself — a  test  which  could  be  apphed 
only  several  years  later,  and  which  developed  into  a  scientific 
event  of  the  highest  importance. 

For  at  the  same  time  that  Einstein  solved  the  problem  of 
Mercury,  he  had  investigated  the  path  of  Ught-rays  according  to 
his  revolutionary  method,  and  had  arrived  at  the  conclusion 
that  every  ray  under  the  influence  of  a  gravitational  field, 
as,  for  example,  in  the  neighbourhood  of  the  sun,  must  become 
curved.  This  daring  announcement  gave  a  new  possibihty  of 
putting  the  theory  to  a  practical  test  during  the  total  eclipse 
of  the  sun  on  29th  May  1919.  For,  when  the  disc  of  the  sun  is 
obscured,  the  stars  that  are  closest  to  it  become  visible  (even 
to  the  naked  eye).  They  may  be  photographed,  and  the 
distances  of  the  points  of  fight  on  the  negative  allow  us  to 
detect  whether  the  rays  from  the  stars  in  passing  the  massive 
body  of  the  sun  have  actually  been  deflected  by  the  amount 
prophesied  by  Einstein. 


PHENOMENA  IN  THE  HEAVENS       11 

Once  again  current  thought  encountered  a  sharp  comer, 
and  "common  sense,"  which  furnishes  its  own  certificate  of 
merit,  threatened  to  become  rebellious.  How  now  ?  A  ray 
from  a  star  could  be  curved  ?  Does  not  this  contradict  the 
elementary  conception  of  the  straight  Hues,  that  is,  the  shortest 
Hues,  for  which  we  have  no  better  picture  than  just  these  rays  ? 
Did  not  Leonardo  da  Vinci  define  the  straight  line  by  means  of 
the  term  linea  radiosa. 

But  such  supposedly  self-evident  facts  have  no  longer  a 
place  in  the  space-time  world.  The  point  was  to  test  whether 
a  physical  anomaly  which  had  been  predicted  actually 
existed.  If  the  deflection  of  the  rays  really  happened,  it 
should  manifest  itself  in  the  distances  between  the  stars  on 
the  photographic  plate  being  greater  than  one  would  expect 
from  their  actual  position. 

For  the  curvature  has  its  concave  side  towards  the  sim, 
as  is  easy  to  see,  once  the  phenomenon  is  regarded  as  possible. 
It  is  as  if  the  ray  were  directly  subject  to  gravitation.  Let  us 
take  two  stars,  one  on  each  side  of  the  sun.  On  account  of 
the  concavities  the  eye  receives  rays  from  them  imder  a  greater 
visual  angle  than  if  the  rays  were  straight,  and  interprets  this 
angle  as  denoting  a  greater  distance  between  the  sources  of 
hght,  that  is,  it  sees  the  two  stars  farther  apart  than  in  the  case 
of  rectilinear  propagation. 

By  how  much  farther  apart  ?  The  preceding  calculation 
and  the  subsequent  direct  observation  demanded  incredible 
dehcacy  of  measurement.  If  we  suppose  the  whole  arc  of  the 
heavens  divided  into  easily  picturable  units  such  as  degrees, 
then  the  apparent  width  of  the  moon  is  about  half  a  degree. 
We  may  still  easily  imagine  the  thirtieth  part  of  this,  namely,  a 
minute  of  arc.  But  the  sixtieth  part  of  the  latter,  the  second 
of  arc,  vanishes  almost  out  of  the  range  of  sense-perception. 
And  it  was  just  this  minute  measure  that  came  into  question, 
for  the  theory  which  had  been  developed  from  pure  thought 
predicted  a  deflection  of  i^  seconds  of  arc.  This  corresponds 
to  about  a  hairbreadth  when  seen  at  a  distance  of  17  yards, 
or  to  the  thickness  of  a  match  at  a  distance  of  over  half  a 
mile. 

One  of  the  greatest  problems  of  the  most  comprehensive 
science  depended  on  this  rmthinkably  small  measure. 


12  EINSTEIN  THE  SEARCHER 

In  no  sense  did  Einstein  himself  entertain  a  possibility  of 
doubt. 

On  repeated  occasions  before  May  1919  I  had  opportunities 
of  questioning  him  on  this  point.  There  was  no  shadow  of  a 
scruple,  no  ominous  fears  clouded  his  anticipations.  Yet 
great  things  were  at  stake. 

Observation  was  to  show  "  the  correctness  of  Einstein's 
world  system  "  by  a  fact  clearly  intelHgible  to  the  whole  world, 
one  depending  on  a  very  sensitive  test  of  less  than  two  seconds 
of  arc. 

"  But,  Professor,*'  said  I,  on  various  occasions,  "  what  if  it 
turns  out  to  be  more  or  less  ?  These  things  are  dependent  on 
apparatus  that  may  be  faulty,  or  on  unforeseen  imperfections 
of  observation."  A  smile  was  Einstein's  only  answer,  and  this 
smile  expressed  his  unshakeable  faith  in  the  instruments  and 
the  observers  to  whom  this  duty  was  to  be  entrusted. 

Moreover,  it  is  to  be  remarked  that  no  great  lengths  of  time 
were  available  for  comfortable  experimentation  in  taking  this 
photographic  record.  For  the  greatest  possible  duration  of  a 
total  eclipse  of  the  sun  viewed  at  a  definite  place  amounts  to 
less  than  eight  minutes,  so  that  there  was  no  room  for  mishaps 
in  this  short  space  of  time,  nor  must  any  intervening  cloud 
appear.  The  kindly  co-operation  of  the  heavens  was  indis- 
pensable— and  was  not  refused.  The  sun,  in  this  case  the 
darkened  sun,  brought  this  fact  to  light. 

Two  English  expeditions  had  been  equipped  for  the  special 
occasion  of  the  echpse — one  to  proceed  to  Sobral  and  the  other 
to  the  Island  of  Principe,  off  Portuguese  Africa ;  they  were 
sent  officially  with  equipment  provided  in  the  main  by  the 
time-honoured  Royal  Society.  Considering  the  times,  it  was 
regarded  as  the  first  symptom  of  the  revival  of  international 
science,  a  praiseworthy  undertaking.  A  huge  apparatus  was 
set  into  motion  for  a  purely  scientific  object  with  not  the 
slightest  relation  to  any  purpose  useful  in  practical  life.  It 
was  a  highly  technical  investigation  whose  real  significance 
could  be  grasped  by  only  very  few  minds.  Yet  interest  was 
excited  in  circles  reaching  far  beyond  that  of  the  professional 
scientist.  As  the  solar  eclipse  approached,  the  consciousness 
of  amateurs  became  stirred  with  indefinite  ideas  of  cosmic 
phenomena.    And  just  as  the  navigator  gazes  at  the  Polar 


PHENOMENA  IN  THE  HEAVENS       13 

Star,  so  men  directed  their  attention  to  the  constellation  of 
Einstein,  which  was  not  yet  depicted  in  stellar  maps,  but,  from 
which  something  imcomprehended,  but  undoubtedly  very 
important,  was  to  blaze  forth. 

In  June  it  was  announced  that  the  star  photographs  had 
been  successful  in  most  cases,  yet  for  weeks,  nay  for  months, 
we  had  to  exercise  patience.  For  the  photographs,  although 
they  required  little  time  to  be  taken,  took  much  longer  to 
develop  and,  above  all,  to  be  measured  ;  in  view  of  the  order  of 
smallness  of  the  distances  to  be  compared,  this  was  a  difficult 
and  troublesome  task,  for  the  points  of  Ught  on  the  plate  did 
not  answer  immediately  with  Yes  or  No,  but  only  after 
mechanical  devices  of  extreme  deUcacy  had  been  carefully 
appUed. 

At  the  end  of  September  they  proclaimed  their  message. 
It  was  in  the  affirmative,  and  this  Yes  out  of  far-distant  tran- 
scendental regions  called  forth  a  resounding  echo  in  the  world 
of  everyday  hfe.  Genuinely  and  truly  the  i^  seconds  of  arc 
had  come  out,  correct  to  the  decimal  point.  These  points 
representing  ciphers,  as  it  were,  had  chanted  of  the  harmony 
of  the  spheres  in  their  Pythagorean  tongue.  The  transmission 
of  this  message  seemed  to  be  accompanied  by  the  echoing 
words  of  Goethe's  **  Ariel  "  : 

"  With  a  crash  the  Light  draws  near ! 
Pealing  rays  and  trumpet-blazes, — 
Eye  is  blinded,  ear  amazes." 

Never  before  had  anything  like  this  happened.  A  wave 
of  amazement  swept  over  the  continents.  Thousands  of 
people  who  had  never  in  their  lives  troubled  about  vibrations 
of  hght  and  gravitation  were  seized  by  this  wave  and  carried 
on  high,  immersed  in  the  wish  for  knowledge  although  in- 
capable of  grasping  it.  This  much  all  understood,  that  from 
the  quiet  study  of  a  scholar  an  illuminating  gospel  for  exploring 
the  universe  had  been  irradiated. 

During  that  time  no  name  was  quoted  so  often  as  that  of 
this  man.  Everything  sank  away  in  face  of  this  universal 
theme  which  had  taken  possession  of  humanity.  The  con- 
verse of  educated  people  circled  about  this  pole,  could  not 
escape  from  it,  continually  reverted  to  the  same  theme  when 


14  EINSTEIN  THE  SEARCHER 

pressed  aside  by  necessity  or  accident.  Newspapers  entered 
on  a  chase  for  contributors  who  could  furnish  them  with  short 
or  long,  technical  or  non-technical,  notices  about  Einstein's 
theory.  In  all  nooks  and  comers  social  evenings  of  instruction 
sprang  up,  and  wandering  universities  appeared  with  errant 
professors  that  led  people  out  the  three-dimensional  misery 
of  daily  life  into  the  more  hospitable  Elysian  fields  of  four- 
dimensionaUty.  Women  lost  sight  of  domestic  worries  and 
discussed  co-ordinate  systems,  the  principle  of  simultaneity, 
and  negatively-charged  electrons.  All  contemporary  questions 
had  gained  a  fixed  centre  from  which  threads  could  be  spun  to 
each.  Relativity  had  become  the  sovereign  password.  In 
spite  of  some  grotesque  results  that  followed  on  this  state  of 
affairs  it  could  not  fail  to  be  recognized  that  we  were  watching 
symptoms  of  mental  hunger  not  less  imperative  in  its  demands 
than  bodily  hunger,  and  it  was  no  longer  to  be  appeased  by 
the  former  books  by  writers  on  popular  science  and  by  mis- 
guided idealists. 

And  whilst  leaders  of  the  people,  statesmen,  and  ministers 
made  vain  efforts  to  steer  in  the  fog,  to  arrive  at  results  service- 
able to  the  nation,  the  multitude  found  what  was  expedient  for 
it,  what  was  upHfting,  what  sounded  like  the  distant  hammer- 
ing of  reconstruction.  Here  was  a  man  who  had  stretched  his 
hands  towards  the  stars  ;  to  forget  earthly  pains  one  had  but 
to  immerse  oneself  in  his  doctrine.  It  was  the  first  time  for 
ages  that  a  chord  vibrated  through  the  world  invoking  all  eyes 
towards  something  which,  like  music  or  rehgion,  lay  outside 
political  or  material  interests. 

The  mere  thought  that  a  Hving  Copernicus  was  moving  in 
our  midst  elevated  our  feelings.  Whoever  paid  him  homage 
had  a  sensation  of  soaring  above  Space  and  Time,  and  this 
homage  was  a  happy  augury  in  an  epoch  so  bare  of  brightness 
as  the  present. 

As  already  remarked,  there  was  no  lack  of  rare  fruits  among 
the  newspaper  articles,  and  a  chronicler  would  doubtless  have 
been  able  to  make  an  attractive  album  of  them.  I  brought 
Einstein  several  foreign  papers  with  large  illustrations  which 
must  certainly  have  cost  the  authors  and  publishers  much 
effort  and  money.    Among  others  there  were  full-page  beauti- 


PHENOMENA  IN  THE  HEAVENS      15 

fully  coloured  pictures  intended  to  give  the  reader  an  idea  of 
the  paths  pursued  by  the  rays  from  the  stars  during  the  total 
echpse  of  the  sun.  These  afforded  Einstein  much  amusement, 
namely,  e  contrario,  for  from  the  physical  point  of  view  these 
pages  contained  utter  nonsense.  They  showed  the  exact  op- 
posite of  the  actual  course  of  the  rays  inasmuch  as  the  author 
of  the  diagrams  had  turned  the  convex  side  of  the  deflected 
ray  towards  the  sun.  He  had  not  even  a  vague  idea  of  the 
character  of  the  deflection,  for  his  rays  proceeded  in  a  straight 
Une  through  the  universe  until  they  reached  the  sun,  where 
they  underwent  a  sudden  change  of  direction  reminiscent  of  a 
stork's  legs.  The  din  of  joumaUstic  homage  was  not  immixed 
with  scattered  voices  of  dissent,  even  of  hostility.  Einstein 
combated  these  not  only  without  anger  but  with  a  certain 
satisfaction.  For  indeed  the  series  of  imbroken  ovations 
became  discomfiting,  and  his  feeUngs  took  up  arms  against 
what  seemed  to  be  developing  into  a  star-artist  cult.  It  was 
Uke  a  breath  of  fresh  air  when  some  column  of  a  chance  news- 
paper was  devoted  to  a  polemic  against  his  theory,  no  matter 
how  unfounded  or  unreasoned  it  may  have  been,  merely 
because  a  dissonant  tone  broke  the  unceasing  chorus  of  praise. 
On  one  occasion  he  even  said  of  a  shrill  disputant,  **  The  man 
is  quite  right  I  "  And  these  words  were  uttered  in  the  most 
natural  manner  possible.  One  must  know  him  personally  if 
one  is  to  imderstand  these  excesses  of  toleration.  So  did 
Socrates  defend  his  opponents. 

In  our  conversation  we  retmned  to  the  original  question, 
and  I  asked  whether  there  was  no  means  of  making  the  deflec- 
tion of  the  ray  intelhgible  to  an  average  person. 

Einstein  replied :  "In  a  very  superficial  manner  this  is 
certainly  possible."  And  with  a  few  strokes  on  the  paper, 
which  I  shall  here  try  to  describe  in  words,  he  gave  his  explana- 
tion in  terms  something  like  the  following  : 

This  square  is  to  denote  the  cross-section  of  a  closed  box 
which  we  imagine  to  be  situated  somewhere  in  the  universe. 
Inside  it  there  fives  a  physicist  who  makes  observations  and 
draws  inferences  from  them.  In  the  course  of  time  he  per- 
ceives, what  is  famifiar  to  all  of  us,  that  every  body  not  sup- 
ported and  left  to  itself,  for  example,  a  stone  that  is  released, 
drops  to  the  floor  with  uniform  acceleration,  that  is,  with  a 


16  EINSTEIN  THE  SEARCHER 

steady  increase  of  velocity  in  going  downwards.  There  are 
two  ways  open  to  him  to  explain  this  phenomenon. 

Firstly,  he  might  suspect — and  this  suspicion  would  be 
most  likely  to  occur  to  him — that  his  box  was  resting  on  some 
body  in  the  heavens.  For  if  indeed  the  box  were  a  cave  in 
some  part  of  the  world,  the  falHng  of  the  stone  would  suggest 
nothing  unusual ;  it  would  be  quite  self-evident  to  every 
occupant,  and  quite  expHcable  to  the  physicist  according  to 
Galilei's  (or  Newton's)  Laws  for  Falling  Bodies.  He  need  not 
necessarily  restrict  himself  to  the  Earth,  for  if  the  box  happened 
to  be  on  some  other  star,  this  phenomenon  of  falling  would 
likewise  occur,  with  greater  or  less  speed,  and  the  body  would 
certainly  fall  with  uniform  acceleration.  Thus  the  physicist 
could  say  :  this  is  an  effect  of  gravitation,  exhibiting  the  pro- 
perty of  weight  which  I  explain  to  myself  as  usual,  as  due  to 
the  attraction  of  a  heavenly  body. 

Secondly,  another  idea  might  strike  him.  For  we  stipulated 
nothing  about  the  position  of  the  box,  and  assumed  only  that 
it  was  to  exist  *'  somewhere  in  the  universe."  The  physicist 
in  the  box  might  reason  as  follows  : 

Supposing  I  am  separted  by  incalculable  distances  from 
every  attracting  heavenly  body,  and  supposing  gravitation 
existed  neither  for  me  nor  for  the  stone  which  I  release  from  my 
hand,  then  it  would  still  be  possible  for  me  to  give  a  complete 
explanation  of  the  phenomena  I  observe.  I  should  only  have 
to  assume  that  the  body  is  moving  with  uniform  acceleration 
"  upwards."  The  motion  previously  interpreted  by  me  as  a 
faUing  "  downwards  "  need  not  take  place  at  all.  The  stone, 
as  an  inert  body,  could  persist  in  its  position  (relative  to  the 
box  or  the  observer),  and  would,  in  spite  of  this,  show  exactly 
the  same  behaviour  when  the  box  moves  with  acceleration 
upwards  as  if  it  were  falUng  with  increasing  velocity  downwards. 

Now  since  our  physicist  has  no  system  which  might  serve 
for  reference  and  orientation,  and  since  in  his  box  which  is  shut 
off  from  the  universe  he  has  no  means  at  his  disposal  of  deter- 
mining whether  he  is  in  the  sphere  of  influence  of  an  attracting 
heavenly  body  or  not,  both  the  above  explanations  are  feasible 
for  him  and  both  are  equally  vaUd,  and  it  is  impossible  for  him 
to  come  to  a  decision  in  his  choice.  He  can  interpret  the 
acceleration  in  either  way,  as  being  upwards  or  downwards, 


PHENOMENA  IN  THE  HEAVENS       17 

connected  to  one  another  by  relativity  ;  a  fundamental  reason 
for  preferring  one  interpretation  to  the  other  cannot  be 
furnished,  since  the  phenomenon  of  faUing  is  represented 
unchanged  whether  he  assumes  the  stone  to  be  falhng  and  the 
box  to  be  at  rest,  or  vice  versa.  This  may  be  generahzed  in 
these  words  : 

At  every  point  of  the  world  the  observed  acceleration  of  a 
body  left  to  itself  may  be  interpreted  either  as  a  gravitational 
or  as  an  inertial  effect — ^that  is,  from  the  point  of  view  of 
physics  we  may  assert  with  equal  right  that  the  system  (the 
box,  the  complex  defining  the  orientation)  from  which  I  ob- 
serve the  event  is  accelerated,  or  that  the  event  takes  place  in 
a  gravitational  field.  The  equal  right  to  these  two  views  is 
called  the  **  Principle  of  Equivalence  "  by  Einstein.  It  asserts 
the  equiv^ence  or  the  identity  of  inertial  and  gravitational 
mass.  If  we  famiharize  ourselves  with  this  identity,  an 
exceedingly  important  road  to  knowledge  is  opened  up  to  our 
consciousness.  We  arrive  at  the  inevitable  conclusion  that 
every  inertial  effect  that  we  perceive  in  bodies,  the  most 
essential  quaHty  of  it,  itself  so  to  speak  in  its  persistent  nature, 
is  to  be  traced  back  to  the  influence  to  which  it  is  subjected 
by  other  bodies.  When  this  has  become  clear  to  us,  we  feel 
impelled  to  inquire  how  a  ray  of  light  would  behave  under  the 
influence  of  gravitation.  Hence  we  return  to  our  physicist  in 
the  box,  and  we  now  know  that  as  a  consequence  of  the 
Principle  of  Equivalence  we  are  free  to  assume  either  that  an 
attracting  heavenly  body,  such  as  the  sim,is  situated  somewhere 
below  the  box,  or  to  refer  the  phenomena  to  the  box  regarded 
as  being  accelerated  upwards.  In  the  box  we  distinguish  the 
floor,  the  ceiUng,  four  waUs,  and  among  these  again,  according 
to  the  position  we  take  up,  the  wall  on  the  left  and  its  opposite 
one  on  the  right. 

We  now  imagine  a  marksman  to  be  outside  the  box  and 
having  no  connexion  with  us,  being  poised  freely  in  space, 
and  suppose  him  to  fire  out  of  a  horizontal  gun  at  the  box  so 
that  the  bullet  pierces  both  the  wall  on  the  left  and  the  wall 
on  the  right.  Now,  if  everything  else  were  to  remain  at  rest, 
the  holes  in  both  walls  would  be  equally  distant  from  the 
floor,  and  the  bullet  would  move  in  a  straight  Une  parallel  to 
the  floor  and  to  the  ceihng.     But,  as  we  have  seen,  all  events 


18  EINSTEIN  THE  SEARCHER 

happen  as  if  the  box  itself  moved  with  constant  acceleration. 
The  bullet  that  requires  time  to  pass  from  one  wall  to  the 
other  thus  finds  that  when  it  reaches  the  wall  on  the  right 
the  latter  has  advanced  a  little,  so  that  the  resulting  hole  is  a 
little  lower  than  that  on  the  left  wall.  This  means  that  the 
flight  of  the  bullet,  according  to  our  observation  in  the  interior 
of  the  box,  is  no  longer  rectihnear.  In  fact,  if  we  trace  the 
bullet  from  point  to  point,  we  should  find  that  for  us,  situated 
in  the  box,  it  would  describe  a  line  bent  downwards,  with  its 
concave  side  to  the  floor. 

Exactly  the  same  thing  happens  with  a  ray  of  Hght  which 
is  emitted  by  a  source  outside  in  a  horizontal  direction  and 
which  traverses  the  space  between  the  walls  (supposed  trans- 
parent). Only  the  velocity  would  be  different.  In  the  course 
of  its  flight  the  ray  would  move  like  a  projectile  that  is  whizzing 
along  at  the  rate  of  180,000  miles  per  second.  But  pro- 
vided sufficiently  delicate  means  of  measurement  are  applied, 
it  should  still  be  possible  to  prove  the  existence  of  an  in- 
finitesimal deflection  from  the  rectihnear  horizontal  path, 
an  insignificant  concavity  towards  the  floor. 

Consequently  this  curvature  of  the  hght-ray  (say,  from  a 
star)  must  also  be  perceptible  in  places  where  it  is  subject  to 
the  influence  of  a  gravitational  field.  If  we  drop  our  imaginary 
picture  of  the  box,  the  argument  is  in  nowise  altered.  A  ray 
from  a  star  which  passes  close  by  the  sun  seems  to  our  per- 
ception to  be  bent  in  towards  the  sun,  and  the  order  of  this 
deflection  can  be  determined  if  sufficiently  deHcate  instru- 
ments be  used.  As  above  remarked,  it  is  a  question  of  detect- 
ing a  difference  of  17  seconds  of  arc,  which  is  to  be  manifested 
as  a  distance  on  the  photographic  plate,  and  is  actually  found 
to  be  present. 

The  fact  that  scientists  are  able  to  detect  this  appears  in 
itself  a  marvel  of  technical  precision  far  in  advance  of  "  spht- 
ting  hairs,"  for  in  comparison  a  single  hair  is,  in  this  case,  to  be 
removed  to  a  considerable  distance  if  we  are  to  use  it  to  give 
an  idea  of  the  size  of  angle  under  consideration.  Fortunately 
stellar  photography  has  been  developed  so  wonderfully  that  in 
every  single  case  extraordinarily  accurate  results  are  got  even 
from  preliminary  measurements. 

In  ordinary  astronomical  practice  it  is  usually  found  that 


PHENOMENA  IN  THE  HEAVENS       19 

a  millimetre  in  linear  measure  on  the  plate  corresponds  to  a 
minute  of  arc.  This  means  that  the  sim's  disc  itself  has  a 
diameter  of  3  centimetres  on  the  photograph.  The  stars 
appear  as  tiny  dots,  which  may  be  sharply  differentiated  in  an 
enlargement.  Stars  of  the  fourteenth  order  of  magnitude  and 
beyond  it  become  visible,  whereas  the  naked  eye  cannot  see 
those  of  order  higher  than  the  sixth.  A  grating  whose  lines 
are  ihr  millimetre  wide  is  copied  on  to  the  plate  to  make  the 
measurement  more  accurate,  so  that  the  positions  of  objects 
can  be  ascertained  with  certainty  to  within  a  few  tenths  of  a 
second  of  arc.  Thus  the  problem  which  was  to  be  solved  by 
the  solar  eclipse  of  1919  lay  within  the  realm  of  possibility  as 
regards  our  means  of  measurement. 

A  copy  of  this  photograph  had  been  sent  to  Einstein  from 
England,  and  he  told  me  of  it  with  evident  pleasure.  He 
continually  reverted  to  the  delightful  little  picture  of  the 
heavens,  quite  fascinated  by  the  thing  itself,  without  the 
sUghtest  manifestation  of  a  personal  interest  in  his  own  success. 
Indeed,  I  may  go  further  and  am  certainly  not  mistaken  in 
saying  his  new  mechanics  did  not  even  enter  his  head,  nor  the 
verification  of  it  by  the  plate  ;  on  the  contrary,  he  displayed 
that  disposition  of  the  mind  which  in  the  case  of  genius  as  well 
as  in  that  of  children  shows  itself  as  naivete.  The  prettiness 
of  the  photograph  charmed  him,  and  the  thought  that  the 
heavens  had  been  drawn  up  as  for  parade  to  be  a  model  for  it. 

All  things  are  repeated  in  the  history  of  life.  In  these 
happenings,  which  mark  the  29th  May  1919  as  a  red-letter  day 
in  the  history  of  science,  we  recognize  a  revival  of  the  Sim 
Myth,  unperceived  by  the  individual,  but  as  an  expression  of 
the  universal  consciousness,  just  as  when  Copernicus  con- 
verted the  geocentric  picture  of  the  imiverse  into  a  helio- 
centric one,  the  Sun  Myth  again  sprang  into  Hfe ;  the  sym- 
boHzation  of  faith  in  the  Hght -giving  and  heat -giving  star. 
This  time  it  has  arisen,  purified  of  all  dross,  scarcely  perceptible 
to  our  senses,  hke  an  aureole  spun  about  the  sun  by  far-distant 
sources  of  Hght,  in  honour  of  a  principle,  and  even  if  most  of 
us  do  not  yet  know  what  a  "  system  of  reference  "  means,  yet 
for  many  such  a  system  has  unconsciously  evolved,  a  thought- 
system  serving  as  a  reference  for  the  development  of  their 
knowledge  when  they  thought  or  spoke  of  Einstein. 


CHAPTER  II 
BEYOND  OUR  POWER 

Useful  and  Latent  Forces. — Connexion  between  Mass,  Energy,  and  Velocity 
of  Light. — Deriving  Power  by  Combustion. — -One  Gramme  of  Coal. — Un- 
obtainable Calories. — Economics  of  Coal. — Hopes  and  Fears. — Dissociated 
Atoms. 

29/A  March  1920 

WE  spoke  of  the  forces  that  are  available  for  man  and 
which  he  derives  from  Nature  as  being  necessary  for 
his  existence  and  for  the  development  of  life.  What 
forces  are  at  our  disposal  ?  What  hopes  have  we  of  elaborating 
our  supply  of  these  forces  ? 

Einstein  first  explained  the  conception  of  energy,  which 
is  intimately  connected  with  the  conception  of  mass  itself. 
Every  amount  of  substance  (I  am  paraphrasing  his  words), 
the  greatest  as  well  as  the  smallest,  may  be  regarded  as  a 
store  of  power,  indeed,  it  is  essentially  identical  with  energy. 
All  that  appears  to  our  senses  and  our  ordinary  understanding 
as  the  visible,  tangible  mass,  as  the  objective  body  corre- 
sponding to  which  we,  in  virtue  of  our  individual  bodies, 
abstract  the  conceptual  outlines,  and  become  aware  of  the 
existence  of  a  definite  copy  is,  from  the  physical  point  of 
view,  a  complex  of  energies.  These  in  part  act  directly,  in  part 
exist  in  a  latent  form  as  strains  which,  for  us,  begin  to  act 
only  when  we  release  them  from  their  state  of  strain  by  some 
mechanical  or  chemical  process,  that  is,  when  we  succeed  in 
converting  the  potential  energy  into  kinetic  energy.  It  may 
be  said,  indeed,  that  we  have  here  a  physical  picture  of  what 
Kant  called  the  "  thing  in  itself."  Things  as  they  appear 
in  ordinary  experience  are  composed  of  the  sum  of  our  direct 
sensations  ;  each  thing  acts  on  us  through  its  outHne,  colour, 
tone,  pressure,  impact,  temperature,  motion,  chemical  be- 
haviour, whereas  the  thing  in  itself  is  the  sum-total  of  its 

energy,  in  which  there  is  an  enormous  predominance  of  those 

20 


BEYOND  OUR  POWER  21 

energies  which  remain  latent  and  are  quite  inaccessible  in 
practice. 

But  this  "  thing  in  itself,"  to  which  we  shall  have  occasion 
to  refer  often  with  a  certain  regard  to  its  metaphysical  sig- 
nificance, may  be  calculated.  The  fact  that  it  is  possible  to 
calculate  it  takes  its  origin,  hke  many  other  things  which  had 
in  no  wise  been  suspected,  in  Einstein's  Theory  of  Relativity. 

Quite  objectively  and  without  betraying  in  the  sHghtest 
degree  that  an  astonishing  world-problem  was  being  dis- 
cussed, Einstein  expressed  himself  thus  : 

"  According  to  the  Theory  of  Relativity  there  is  a  calcul- 
able relation  between  mass,  energy,  and  the  velocity  of  Ught. 
The  velocity  of  hght  (denoted  by  c,  as  usual)  is  equal  to 
3*io^°  cm.  per  second.  Accordingly  the  square  of  c  is  equal 
to  9  times  lo^^  cm.  per  second,  or,  in  round  numbers,  lo^^  cm. 
per  second.  This  c^  plays  an  essential  part  if  we  introduce  into 
the  calculation  the  mechanical  equivalent  of  heat,  that  is, 
the  ratio  of  a  certain  amount  of  energy  to  the  heat  theoretically 
derivable  from  it ;  we  get  for  each  gramme  20*10^2^  that  is, 
20  bilHon  calories." 

We  shall  have  to  explain  the  meaning  of  this  brief  physical 
statement  in  its  bearing  on  our  practical  Uves.  It  operates 
with  only  a  small  array  of  symbols,  and  yet  encloses  a  whole 
universe,  widening  our  perspective  to  a  world-wide  range  ! 

To  simpUfy  the  reasoning  and  make  it  more  evident  we 
shall  not  think  of  the  conception  of  substance  as  an  iUimitable 
whole,  but  shall  fix  our  ideas  on  a  definite  substance,  say  coal. 

There  seems  Uttle  that  may  strike  us  when  we  set  down  the 
words  : 

"  One  Gramme  of  Coal." 

We  shall  soon  see  what  this  one  gramme  of  coal  conveys 
when  we  translate  the  above-mentioned  numbers  into  a 
language  to  which  a  meaning  may  be  attached  in  ordinary 
Ufe.  I  endeavoured  to  do  this  during  the  above  conversa- 
tion, and  was  grateful  to  Einstein  for  agreeing  to  simpUfy  his 
argument  by  confining  his  attention  to  the  most  valuable  fuel 
in  our  economic  life. 

Once  whilst  I  was  attending  a  students*  meeting,  paying 
homage  to  Wilhelm  Dove,  the  celebrated  discoverer  took  us 
aback  with  the  following  remark  :   When  a  man  succeeds  in 


22  EINSTEIN  THE  SEARCHER 

climbing  the  highest  mountain  of  Europe  he  performs  a  task 
which,  judged  from  his  personal  point  of  view,  represents 
something  stupendous.  The  physicist  smiles  and  says  quite 
simply,  "  Two  pounds  of  coal."  He  means  to  say  that  by 
burning  2  lb.  of  coal  we  gain  sufQcient  energy  to  lift  a  man 
from  the  sea-level  to  the  summit  of  Mont  Blanc. 

It  is  assumed,  of  course,  that  an  ideal  machine  is  used, 
which  converts  the  heat  of  combustion  without  loss  into  work. 
Such  a  machine  does  not  exist,  but  may  easily  be  imagined  by 
supposing  the  imperfections  of  machines  made  by  human 
hands  to  be  eUminated. 

Such  effective  heat  is  usually  expressed  in  calories.  A  calorie 
is  the  amount  of  heat  that  is  necessary  to  raise  the  tempera- 
ture of  a  gramme  of  water  by  one  degree  centigrade.  Now 
the  theorem  of  the  Mechanical  Equivalent,  which  is  founded 
on  the  investigations  of  Camot,  Robert  Mayer,  and  Clausius, 
states  that  from  one  calorie  we  may  obtain  sufficient  energy 
to  lift  a  pound  weight  about  3  feet.  Since  2  lb.  of  coal 
may  be  made  to  yield  8  million  calories,  they  will  enable 
us  to  lift  a  pound  weight  through  24  milHon  feet,  theoretically, 
or,  what  comes  to  the  same  approximately,  to  hft  a  17- 
stone  man  through  100,000  feet,  that  is,  nearly  19  miles  : 
this  is  nearly  seven  times  the  height  of  Mont  Blanc. 

At  the  time  when  Dove  was  lecturing,  Einstein  had  not 
yet  been  born,  and  when  Einstein  was  working  out  his  Theory 
of  Relativity,  Dove  had  long  passed  away,  and  with  him  there 
vanished  the  idea  of  the  small  value  of  the  energy  stored 
in  substance  to  give  way  to  a  very  much  greater  value  of 
which  we  can  scarce  form  an  estimate.  We  should  feel  dumb- 
founded if  the  new  calculation  were  to  be  a  matter  of  millions, 
but  actually  we  are  to  imagine  a  magnification  to  the  extent 
of  bilHons.  This  sounds  almost  hke  a  fable  when  expressed 
in  words.  But  a  milHon  is  related  to  a  bilHon  in  about  the 
same  way  as  a  fairly  wide  city  street  to  the  width  of  the  Atlantic 
Ocean.  Our  Mont  Blanc  sinks  to  insignificance.  In  the  above 
calculation  it  would  have  to  be  replaced  by  a  mountain 
50  miUion  miles  high.  Since  this  would  lead  far  out  into 
space,  we  may  say  that  the  energy  contained  in  a  kilogramme 
of  coal  is  sufficient  to  project  a  man  so  far  that  he  will  never 
return,  converting  him  into  a  human  comet.     But  for  the 


BEYOND  OUR  POWER  23 

present  this  Is  only  a  theoretical  store  of  energy  which  cannot 
yet  be  utilized  in  practice. 

Nevertheless,  we  cannot  avoid  it  in  our  calculations  just 
as  we  cannot  avoid  that  remarkable  quantity  c,  the  velocity 
of  Hght  that  plays  its  part  in  the  tiny  portion  of  substance  as 
it  does  in  everything,  asserting  itself  as  a  regulative  factor 
in  all  world  phenomena.  It  is  a  natural  constant  that  pre- 
serves itself  unchanged  as  180,000  miles  per  second  under 
all  conditions,  and  which  truly  represents  what  appeared  to 
Goethe  as  "  the  immovable  rock  in  the  surging  sea  of  pheno- 
mena," as  a  phantasm  beyond  the  reach  of  investigators. 

It  is  difficult  for  one  who  has  not  been  soaked  in  all  the 
elements  of  physical  thought  to  get  an  idea  of  what  a  natural 
constant  means  ;  so  much  the  more  when  he  feels  himself 
imf)elled  to  picture  the  constant,  so  to  speak,  as  the  rigid  axis 
of  a  world  constructed  on  relativity.  Everything,  without 
exception,  is  to  be  subjected  not  only  to  continual  change  (and 
this  was  what  HeracHtus  assumed  as  a  fundamental  truth  in 
his  assertion  fanta  rhei,  everything  flows),  but  every  length- 
measurement  and  time-measurement,  every  motion,  every 
form  and  figure  are  dependent  on  and  change  with  the  position 
of  the  observer,  so  that  the  last  vestige  of  the  absolute  vanishes 
from  whatever  comes  into  the  realm  of  observation.  Never- 
theless, there  is  an  absolute  despot,  who  preserves  his  identity 
inflexibly  among  all  phenomena — ^the  velocity  of  hght,  c,  of 
incalculable  influence  in  practice  and  yet  capable  of  measure- 
ment. Its  nature  has  been  characterized  in  one  of  the  main 
propositions  of  Einstein  stated  in  1905  :  '*  Every  ray  of  hght 
is  propagated  in  a  system  at  rest  with  a  definite,  constant 
velocity  independent  of  whether  the  ray  is  emitted  by  a  body 
at  rest  or  in  motion.'*  But  this  constancy  of  the  omnipotent 
c  is  not  only  in  accordance  with  world  relativity :  it  is  actually 
the  main  pillar  which  supports  the  whole  doctrine  ;  the  further 
one  penetrates  into  the  theory,  the  more  clearly  does  one  feel 
that  it  is  just  this  c  which  is  responsible  for  the  unity,  con- 
nectivity, and  invincibiUty  of  Einstein's  world  system. 

In  our  example  of  the  coal,  from  which  we  started,  c  occurs 
as  a  square,  and  it  is  as  a  result  of  multiplying  300,000  by  itself 
(that  is,  forming  c^)  that  we  arrive  at  the  thousands  of  miUiards 
of  energy  imits  which  we  associated  above  with  such  a  com- 


24  EINSTEIN  THE  SEARCHER 

paratively  insignificant  mass.  Let  us  picture  this  astounding 
circumstance  in  another  way,  although  we  shall  soon  see  that 
Einstein  clips  the  wings  of  our  soaring  imagination.  The  huge 
ocean  liner  Imperator,  which  can  develop  a  greater  horse- 
power than  could  the  whole  of  the  Prussian  cavalry  before  the 
war,  used  to  require  for  one  day's  travel  the  contents  of  two 
very  long  series  of  coal-trucks  (each  series  being  as  long  as  it 
takes  the  strongest  locomotive  to  pull).  We  now  know  that 
there  is  enough  energy  in  two  pounds  of  coal  to  enable  this 
boat  to  do  the  whole  trip  from  Hamburg  to  New  York  at  its 
maximum  speed. 

I  quoted  this  fact,  which,  although  it  sounds  so  incredibly 
fantastic,  is  quite  true,  to  Einstein  with  the  intention  of  justi- 
iymg  the  opinion  that  it  contained  the  key  to  a  development 
which  would  initiate  a  new  epoch  in  history  and  would  be  the 
panacea  of  all  human  woe.  I  drew  an  enthusiastic  picture  of  a 
dazzUng  Utopia,  an  orgy  of  hopeful  dreams,  but  immediately 
noticed  that  I  received  no  support  from  Einstein  for  these 
visionary  aspirations.  To  my  disappointment,  indeed,  I 
perceived  that  Einstein  did  not  even  show  a  special  interest  in 
this  circumstance  which  sprang  from  his  own  theory,  and  which 
promised  such  bountiful  gifts.  And  to  state  the  conclusion  of 
the  story  straight  away  I  must  confess  that  his  objections  were 
strong  enough  not  only  to  weaken  my  rising  hopes,  but  to 
annihilate  them  completely. 

Einstein  commenced  by  sd^ymg  :  "At  present  there  is 
not  the  slightest  indication  of  when  this  energy  will  be  ob- 
tainable, or  w^^ether  it  will  be  obtainable  at  all.  For  it 
would  presuppose  a  disintegration  of  the  atom  effected  at  will 
— a  shattering  of  the  atom.  And  up  to  the  present  there  is 
scarcely  a  sign  that  this  will  be  possible.  We  observe  atomic 
disintegration  only  where  Nature  herself  presents  it,  as  in  the 
case  of  radium,  the  activity  of  which  depends  upon  the  con- 
tinual explosive  decomposition  of  its  atom.. ^-Nevertheless,  we 
can  only  establish  the  presence  of  this  proems,  but  cannot  pro- 
duce it ;  Science  in  its  present  state  majkes  it  appear  almost 
impossible  that  we  shall  ever  succeed  in  BQt^oing." 

The  fact  that  we  are  able  to  abstract  a  certain  number  of 
calories  from  coal  and  put  them  to  practical  use  comes  about 
owing  to  the  circumstance  that  combustion  is  only  a  molecular 


BEYOND  OUR  POWER  26 

process,  a  change  of  configuration,  which  leaves  fully  intact  the 
atoms  of  which  the  molecules  are  composed.  When  carbon 
and  oxygen  combine,  the  elementary  constituent,  the  atom, 
remains  quite  unimpaired.  The  above  calculation,  **  mass 
multipUed  by  the  square  of  the  velocity  of  Hght,"  would  have 
a  technical  significance  only  if  we  were  able  to  attack  the 
interior  of  the  atom  ;  and  of  this  there  seems,  as  remarked,  not 
the  remotest  hope. 

Out  of  the  history  of  technical  science  it  might  seem  possible 
to  draw  on  examples  contradictory  to  this  first  argument 
which  is  soon  to  be  followed  by  others  equally  important.  As  a 
matter  of  fact,  rigorous  science  has  often  declared  to  be  impos- 
sible what  was  later  discovered  to  be  within  the  reach  of  tech- 
nical attainment — things  that  seem  to  us  nowadays  to  be 
ordinary  and  self-evident.  Werner  Siemens  considered  it 
impossible  to  fly  by  means  of  machines  heavier  than  air,  and 
Helmholtz  proved  mathematically  that  it  was  impossible. 
Antecedent  to  the  discovery  of  the  locomotive  the  **  impossible  " 
of  the  academicians  played  an  important  part ;  Stephenson 
as  well  as  Riggenbach  (the  inventors  of  the  locomotive)  had 
no  easy  task  to  estabUsh  their  inventions  in  the  face  of  the 
general  reproach  of  craziness  hurled  at  them.  The  eminent 
physicist  Babinet  appUed  his  mathematical  artillery  to 
demoHsh  the  ideas  of  the  advocates  of  a  telegraphic  cable 
between  Europe  and  America.  Phihpp  Reis,  the  forerunner 
of  the  telephone,  failed  only  as  a  result  of  the  "  impossible  "  of 
the  learned  physicist  Poggendorff ;  and  even  when  the  prac- 
tical telephone  of  Graham  Bell  (1876)  had  been  found  to  work 
in  Boston,  on  this  side  of  the  Atlantic  there  was  still  a  hubbub 
of  **  impossible  "  owing  to  scientific  reasons.  To  these  illustra- 
tions is  to  be  added  Robert  Mayer's  mechanical  equivalent  of 
heat,  a  determining  factor  in  our  above  calculations  of  billions  ; 
it  Hkewise  had  to  overcome  very  strong  opposition  on  the  part 
of  leading  scientists. 

Let  us  imagine  the  state  of  mankind  before  the  advent  of 
machines  and  before  coal  had  been  made  available  as  a  source 
of  power.  Even  at  that  time  a  far-seeing  investigator  would 
have  been  able  to  discover  from  theoretical  grounds  the  8000 
calories  mentioned  earUer  and  also  their  transformation  into 
useful  forces.     He  would  have  expressed  it  in  another  way  and 


26  EINSTEIN  THE  SEARCHER 

would  have  got  different  figures,  but  he  would  have  arrived 
at  the  conclusion  :  Here  is  a  virtual  possibility  which  must 
unfortunately  remain  virtual,  as  we  have  no  machine  in  which 
it  can  be  used.  And  however  far-sighted  he  may  have  been, 
the  idea  of,  say,  a  modern  dynamo  or  a  turbine-steamer  would 
have  been  utterly  inconceivable  to  him.  He  would  not  have 
dreamed  such  a  thing.  Nay,  we  may  even  imagine  a  human 
being  of  the  misty  dawn  of  prehistoric  ages,  of  the  diluvial 
period,  who  had  suddenly  had  a  presentiment  of  the  connexion 
between  a  log  of  wood  and  the  sun's  heat,  but  who  was  yet 
unaware  of  the  uses  of  fire  ;  he  would  argue  from  his  prim- 
ordial logic  that  it  was  not  possible  and  never  would  be  possible 
to  derive  from  the  piece  of  wood  something  which  sends  out 
warmth  Uke  the  sun. 

I  believe  now,  indeed,  that  we  have  grounds  for  consider- 
ing ourselves  able  to  mark  off  the  limits  of  possibiUty  more 
clearly  than  the  present  position  of  science  would  seem  to 
warrant.  There  is  the  same  relation  between  such  possibiHties 
and  absolute  impossibihties  as  there  is  between  Leibniz's 
veriUs  de  fait  and  the  verites  eternelles.  The  fact  that  we  shall 
never  succeed  in  constructing  a  plane  isosceles  triangle  with 
unequal  base  angles  is  a  verite  eternelle.  On  the  other  hand, 
it  is  only  a  verite  de  fait  that  science  is  precluded  from  giving 
mortal  man  eternal  Hfe.  This  is  only  improbable  in  the  highest 
degree,  for  the  fact  that,  up  to  the  present,  all  our  ancestors 
have  died  is  only  a  finite  proof.  The  well-known  Cajus  of  our 
logic  books  need  not  die  ;   the  chances  of  his  dying  are  only 

—TT*  where  we  denote  the  total  of  all  persons  that  have  passed 

away  up  to  this  moment  by  n.  If  I  ask  a  present-day 
authority  in  biology  or  medicine  what  evidence  there  is  that 
it  will  be  possible  to  preserve  an  individual  person  permanently 
from  death,  he  would  confess  :  not  the  slightest.  Nevertheless, 
Helmholtz  declared  :  "  To  a  person  who  tells  me  that  by  using 
certain  means  the  life  of  a  person  may  be  prolonged  indefinitely 
I  can  oppose  my  extreme  disbehef,  hut  I  cannot  contradict  him 
absolutely.** 

Einstein  himself  once  pointed  out  to  me  such  very  remote 
possibiHties ;  it  was  in  connexion  with  the  following  cir- 
cumstance.    It  is  quite  impossible  for  a  moving  body  ever 


BEYOND  OUR  POWER  27 

to  attain  a  velocity  greater  than  that  of  light,  because  it  is 
scientifically  inconceivable.  On  the  other  hand,  it  is  con- 
ceivable, and  therefore  within  the  range  of  possibiUty,  that 
man  may  yet  fly  to  the  most  distant  constellations. 

There  is,  therefore,  no  absolute  contradiction  to  the  notion 
of  making  available  for  technical  purposes  the  biUions  of 
calories  that  occurred  in  our  problem.  As  soon  as  we  admit  it 
as  possible  for  discussion,  we  find  ourselves  inquiring  what 
the  solution  of  the  problem  could  signify.  In  our  intercourse 
we  actually  arrived  at  this  question,  and  discovered  the  most 
radical  answer  in  a  dissertation  which  Friedrich  Siemens  has 
written  about  coal  in  general  without  touching  in  the  slightest 
on  these  possibihties  of  the  future.  I  imagine  that  this  dis- 
sertation was  a  big  trump  in  my  hand,  but  had  soon  to  learn 
from  the  reasoned  contradiction  of  Einstein  that  the  point 
at  issue  was  not  to  be  decided  in  this  way. 

Nevertheless,  it  will  repay  us  to  consider  these  arguments 
for  a  moment. 

Friedrich  Siemens  starts  from  two  premises  which  he 
seemingly  bases  on  scientific  reasoning,  thus  claiming  their 
vaHdity  generally.  They  are  :  Coal  is  the  measure  of  all 
things.  The  price  of  every  product  represents,  directly  or 
indirectly,  the  value  of  the  coal  contained  in  it. 

As  all  economic  values  in  over-populated  countries  are 
the  result  of  work,  and  as  work  presupposes  coal,  capital  is 
synonymous  with  coal.  The  economic  value  of  each  object 
is  the  sum-total  of  the  coal  that  had  to  be  used  to  manufacture 
the  object  in  question.  In  over-populated  states  each  wage 
is  the  value  of  the  coal  that  is  necessary  to  make  this  extra  life 
possible.  If  there  is  a  scarcity  of  coal,  the  wages  go  down  in 
value  ;  if  there  is  no  coal,  the  wages  are  of  no  value  at  all,  no 
matter  how  much  paper  money  be  issued. 

As  soon  as  agriculture  requires  coal  (this  occurs  when  it  is 
practised  intensively  and  necessitates  the  use  of  railways, 
machines,  artificial  manures),  coal  becomes  involved  with 
food-stuffs.  Thanks  to  industriaUsm,  coal  is  involved  in 
clothing  and  housing,  too. 

Since  money  is  equivalent  to  coal,  proper  administration 
of  finance  is  equivalent  to  a  proper,  administration  of  coal 
resources,   and    our   standard   of    currency   is   in   the    last 


28  EINSTEIN  THE  SEARCHER 

instance  a  coal-currency.  Gold  as  money  is  now  concen- 
trated coal. 

The  most  advanced  people  is  that  which  derives  from  one 
kilogramme  of  coal  the  greatest  possibilities  conducive  to  life. 
Wise  statesmanship  must  resolve  itself  into  wise  administra- 
tion of  coal.  Or,  as  it  has  been  expressed  in  other  words  else- 
where :   "  We  must  think  in  terms  of  coal." 

These  fundamental  ideas  were  discussed,  and  the  result 
was  that  Einstein  admitted  the  premises  in  the  main,  but 
failed  to  see  the  conclusiveness  of  the  inferences.  He  proved 
to  me,  step  by  step,  that  Siemens'  hue  of  thought  followed  a 
vicious  circle,  and,  by  begging  the  question,  arrived  at  a  false 
conclusion.  The  essential  factor,  he  said,  is  man-power,  and 
so  it  will  remain  ;  it  is  this  that  we  have  to  regard  as  the 
primary  factor.  Just  so  much  can  be  saved  to  advantage  as 
there  is  man-power  available  for  purposes  other  than  for  the 
production  of  coal  from  which  they  are  now  released.  If  we 
succeed  in  getting  greater  use  out  of  a  kilogramme  of  coal  by 
better  management,  then  this  is  measurable  in  man-power, 
with  which  one  may  dispense  for  the  mining  of  coal,  and  which 
may  be  applied  to  other  purposes. 

If  the  assertion  :  '*  Coal  is  the  measure  of  all  things," 
were  generally  vahd,  it  should  stand  every  test.  We  need 
only  try  it  in  a  few  instances  to  see  that  the  thesis  does  not 
apply.  For  example,  said  Einstein :  However  much  coal 
we  may  use,  and  however  cleverly  we  may  dispose  of  it,  it  will 
not  produce  cotton.  Certainly  the  freightage  of  cotton-wool 
could  be  reduced  in  price,  but  the  value-factor  represented  by 
man-power  can  never  disappear  from  the  price  of  the  cotton. 

The  most  that  can  be  admitted  is  that  an  increase  of  the 
amount  of  power  obtained  from  coal  would  make  it  possible 
for  more  people  to  exist  than  is  possible  at  present,  that  is,  that 
the  margin  of  over-population  would  become  extended.  But 
we  must  not  conclude  that  this  would  be  a  boon  to  mankind. 
"  A  maximum  is  not  an  optimum." 

He  who  proclaims  the  maximum  without  qualification  as 
the  greatest  measure  of  good  is  like  one  who  studies  the  various 
gases  in  the  atmosphere  to  ascertain  their  good  or  bad  effect 
on  our  breathing,  and  arrives  at  the  conclusion  :  the  nitrogen 
in  the  air  is  harmful,  so  we  must  double  the  proportion  of 


BEYOND  OUR  POWER  29 

oxygen  to  counteract  it ;  this  will  confer  a  great  benefit  on 
humanity ! 

*  Armed  with  this  striking  analogy,  we  can  now  subject 
the  foundation  of  Siemens'  theory  to  a  new  scrutiny,  and  we 
shall  then  discover  that  even  the  premises  contain  a  trace  of 
the  petitio  principii  that  finally  receives  expression  in  the 
radical  and  one-sided  expression  :   "  Coal  is  everything." 

As  if  built  on  soUd  foundations  this  first  statement  looms 
before  us  :  Coal  is  solar  energy.  This  is  so  far  indisputable. 
For  all  the  coal  deposits  that  are  still  slumbering  in  the  earth 
were  once  stately  plants,  dense  woods  of  fern,  which,  bearing 
the  burden  of  milUons  of  years,  have  saved  up  for  us  what 
they  had  once  extracted  as  nutrition  from  the  sun's  rays.  We 
may  let  the  parallel  idea  pass  without  contention  :  In  the 
beginning  was  not  the  Word,  nor  the  Deed,  but,  in  the  be- 
ginning was  the  Sun.  The  energy  sent  out  by  the  sun  to  the 
earth  for  mankind  is  the  only  necessary  and  inevitable  con- 
dition for  deeds.  Deeds  mean  work,  and  work  necessitates 
fife.  But  we  immediately  become  involved  in  an  unjustifiable 
subdivision  of  the  idea,  for  the  propounder  of  the  theory  says 
next  :  "...  Coal  is  solar  energy,  therefore  coal  is  necessary 
if  we  are  to  work  ..."  and  this  has  already  thrust  us  from 
the  paths  of  logic  ;  the  prematurely  victorious  ergo  breaks 
down.  For,  apart  from  the  solar  energy  converted  into  coal, 
the  warmth  of  our  mother  planet  radiates  on  us,  and  furnishes 
us  with  the  possibiUty  of  work.  Siemens*  conclusion,  from 
the  point  of  view  of  logic,  is  tantamount  to  :  Graphite  is  solar 
energy ;  hence  graphite  is  necessary,  if  we  are  to  be  able  to 
work.     The  true  expression  of  the  state  of  affairs  is  :  Coal  is, 

♦  The  parts  included  between  *  ...  *  axe  to  be  regarded  as  supplementary 
portions  intended  to  elucidate  the  arguments  involved  in  the  dialogue.  In 
many  points  they  are  founded  on  utterances  of  Einstein,  but  also  contain 
reflections  drawn  from  other  sources,  as  well  as  opinions  and  inferences  which 
fall  to  the  account  of  the  author,  as  already  remarked  in  the  preface.  One 
will  not  get  far  by  judging  these  statements  as  right  or  wrong,  for  even  the 
debatable  view  may  prove  itself  to  be  expeditious  and  suggestive  in  the 
perspective  of  these  conversations.  Wherever  it  was  possible,  without  the 
connexion  being  broken,  I  have  called  attention  to  the  parts  which  Einstein 
corrected  or  disapproved  of.  In  other  places  I  refrained  from  this,  particu- 
larly when  the  subject  under  discussion  demanded  an  even  flow  of  argument. 
It  would  have  disturbed  the  exposition  if  I  had  made  mention  of  every 
counter-argument  of  the  opposing  side  in  all  such  cases  while  the  explanation 
was  proceeding  along  broad  lines. 


80  EINSTEIN  THE  SEARCHER 

for  our  present  conditions  of  life,  the  most  important,  if  not  the 
exclusive,  preliminary  for  human  work. 

And  when  we  learn  from  political  economy  that  "  in  a 
social  state  only  the  necessary  human  labour  and  the  demand 
for  power-installations  which  require  coal,  and  hence  again 
labour  for  their  production,  come  into  question,"  this  in  no 
way  implies  the  assertion,  as  Siemens  appears  to  assume,  that 
coal  can  be  made  out  of  labour.  But  it  does  signify  that  work 
founded  on  the  sun's  energy  need  not  necessarily  be  reducible 
to  coal.  And  this  probably  coincides  with  Einstein's  opinion, 
which  is  so  much  the  more  significant,  as  his  own  doctrine 
points  to  the  highest  measure  of  effect  in  forces,  even  if  only 
theoretically.* 

Nevertheless,  it  is  a  fact  that  every  increase  in  the  quantity 
of  power  derived,  when  expressed  per  kilo,  denotes  a  mitiga- 
tion of  life's  burdens  ;  it  is  only  a  question  of  the  limits 
involved. 

Firstly,  is  technical  science  with  its  possibilities,  as  far  as 
they  can  be  judged  at  present,  still  able  to  guarantee  the 
future  for  us  ?  Can  it  spread  out  the  effective  work  so  far 
that  we  may  rely  peacefully  on  the  treasures  of  coal  slumbering 
in  the  interior  of  the  earth  ? 

Evidently  not.  For  in  this  case  we  are  deaUng  with 
quantities  that  may  be  approximately  estimated.  And  even 
if  we  get  three  times,  nay  ten  times,  as  many  useful  calories 
as  before,  there  is  a  parallel  calculation  of  evil  omen  that  in- 
forms us  :  there  will  be  an  end  to  this  feast  of  energy. 

In  spite  of  all  the  embarrassments  due  to  the  present 
shortage  of  coal  we  have  still  always  been  able  to  console 
ourselves  with  the  thought  that  there  is  really  a  sufficiency, 
and  that  it  is  only  a  question  of  overcoming  stoppages.  It  is 
a  matter  of  fact  that  from  the  time  of,  the  foundation  of  the 
German  Empire  to  the  beginning  of  the  World  War  coal 
production  had  been  rising  steadily,  and  it  was  possible  to 
calculate  that  in  spite  of  the  stupendous  quantities  that 
were  being  removed  from  the  black  caves  of  Germany,  there 
remained  at  least  2000  milHards  of  marks  in  value  (taken 
at  the  nominal  rate,  that  is,  £100,000,000,000).  Never- 
theless, geologists  and  mining  experts  tell  us  that  our  whole 
supply  will  not  last  longer  than  2000  years,  in  the  case  of 


BEYOND  OUR  POWER  81 

England  500  years,  and  in  that  of  France  200  years.  Even 
if  we  allow  amply  for  the  opening  up  of  new  coal-fields  in  other 
continents,  we  cannot  get  over  the  fact  that  in  the  prehistoric 
fern  forests  the  sun  has  stored  up  only  a  finite,  exhaustible 
amount  of  energy,  and  that  within  a  few  hundred  years 
humanity  will  be  faced  with  a  coal  famine. 

Now,  if  coal  were  really  the  measure  of  all  things,  and  if 
the  possibiHty  of  life  depended  only  on  the  coal  supply,  then 
our  distant  descendants  would  not  only  relapse  into  barbarity, 
but  they  would  have  to  expect  the  absolute  zero  of  existence. 
We  should  not  need  to  worry  at  all  about  the  entropy  death 
of  the  imiverse,  as  our  own  extinction  on  this  earthly  planet 
beckons  to  us  from  an  incomparably  nearer  point  of  time. 

At  this  stage  of  the  discussion  Einstein  revealed  prospects 
which  were  entirely  in  accordance  with  his  conviction  that  the 
whole  argument  based  on  the  coal  assumption  was  imtenable. 
He  stated  that  it  was  by  no  means  a  Utopian  idea  that  technical 
science  will  yet  discover  totally  new  ways  of  setting  free 
forces,  such  as  using  the  sim's  radiation,  or  water  power,  or 
the  movement  of  the  tides,  or  power  reservoirs  of  Nature, 
among  which  the  present  coal  supply  denotes  only  one  branch. 
Since  the  beginning  of  coal  extraction  we  have  hved  only  on 
the  remains  of  a  prehistoric  capital  that  has  lain  in  the 
treasure-chests  of  the  earth.  It  is  to  be  conjectured  that  the 
interest  on  the  actual  capital  of  force  will  be  very  much  in 
excess  of  what  we  can  fetch  out  of  the  depositories  of  former 
ages. 

To  form  an  estimate  of  this  actual  capital,  entirely  in- 
dependent of  coal,  we  may  present  some  figmres.  Let  us 
consider  a  tiny  water  canal,  a  mere  nothing  in  the  watery 
network  of  the  earth,  fhe  Rhine-falls  at  Schaffliausen,  that 
may  appear  mighty  to  the  beholder,  but  only  because  he 
appHes  his  tourist's  measure  instead  of  a  planetary  one.  But 
even  this  bagatelle  in  the  household  of  Nature  represents  very 
considerable  effectual  values  for  us  :  200  cubic  metres  spread 
over  a  terrace  20  metres  high  yield  67,000  horse-power,  equi- 
valent to  50,000  kilowatts.  This  cascade  alone  would  suffice 
to  keep  illuminated  to  their  full  intensity  1,000,000  glow- 
lamps,  each  of  50  candle-power,  and  according  to  our  present 
tariff  we  should  have  to  pay  at  least  70,000  marks  (;£35oo 


82  EINSTEIN  THE  SEARCHER 

nominally)  per  hour.  The  coal-worshipper  will  be  more  im- 
pressed by  a  different  calculation.  The  Rhine-falls  at  Schaff- 
hausen  is  equivalent  in  value  to  a  mine  that  yields  every  day 
145  tons  of  the  finest  brown  coal.  If  we  took  the  Niagara 
Falls  as  an  illustration,  these  figures  would  have  to  be  multi- 
plied by  about  80. 

And  by  what  factor  would  we  have  to  multiply  them,  if 
we  wished  to  get  only  an  approximate  estimate  of  the  energy 
that  the  breathing  earth  rolls  about  in  the  form  of  the  tides  ? 
The  astronomer  Bessel  and  the  philosopher-physicist  Fechner 
once  endeavoured  to  get  at  some  comparative  picture  of  these 
events.  It  required  360,000  men  twenty  years  to  build  the 
greatest  Egyptian  pyramid,  and  yet  its  cubical  contents  are 
only  about  the  milHonth  of  a  cubic  mile,  and  perhaps  if  we  sum 
up  everything  that  men  and  machinery  have  moved  since 
the  time  of  the  Flood  till  now,  a  cubic  mile  would  not  yet  have 
been  completed.  In  contrast  with  this,  the  earth  in  its  tidal 
motion  moves  200  cubic  miles  of  water  from  one  quadrant  of 
the  earth's  circumference  to  another  in  every  quarter  of  a  day. 
From  this  we  see  at  once  that  all  the  coal-mines  in  the  world 
would  mean  nothing  to  us  if  we  could  once  succeed  in  making 
even  a  fraction  of  the  pulse-beat  of  the  earth  available  for 
purposes  of  industry. 

If,  however,  we  should  be  compelled  to  depend  on  coal, 
our  imaginations  cling  so  much  more  closely  to  that  enormous 
quantity  given  by  the  expression  mc^,  which  was  derived  from 
the  theory  of  relativity. 

The  20  bilUon  calories  that  are  contained  in  each  gramme 
of  coal  exercise  a  fascination  on  our  minds.  And  although 
Einstein  states  that  there  is  not  the  slightest  indication  that 
we  shall  get  at  this  supply,  we  get  carried  along  by  an  irre- 
sistible impulse  to  picture  what  it  would  mean  if  we  should 
actually  succeed  in  tapping  it.  The  transition  from  the  golden 
to  the  iron  age,  as  pictured  in  Hesiod,  Aratus,  and  Ovid,  takes 
shape  before  our  eyes,  and  following  our  bent  of  continuing 
this  cyclically,  we  take  pleasure  in  fancying  ourselves  being 
rescued  from  the  serfdom  of  the  iron  and  of  the  coal  age  to  a 
new  golden  age.  A  supply,  such  as  is  piled  up  in  an  average 
city  storing-place,  would  be  sufficient  to  supply  the  whole 
world  with  energy  for  an  immeasurable  time.     All  the  troubles 


BEYOND  OUR  POWER  S3 

and  miseries  arising  from  the  running  of  machines,  the 
mechanical  production  of  wares,  house-fires  would  vanish,  and 
all  the  human  labour  at  present  occupied  in  mining  coal  would 
become  free  to  cultivate  the  land,  all  railways  and  boats  would 
run  almost  without  expense,  an  inconceivable  wave  of  happi- 
ness would  sweep  over  mankind.  It  would  mean  an  end  of 
coal-,  freight-,  and  food-shortage  !  We  should  at  last  be  able 
to  escape  out  of  the  hardships  of  the  day,  which  is  broken 
up  by  strenuous  work,  and  soar  upwards  to  brighter  spheres 
where  we  would  be  welcomed  by  the  true  values  of  Hfe.  How 
alluring  is  the  song  of  Sirens  chanted  by  our  physics  with  its 
high  "  C,"  the  velocity  of  hght  to  the  second  power,  which 
we  have  got  to  know  as  a  factor  in  this  secret  store  of  energy. 

But  these  dreams  are  futile.  For  Einstein,  to  whom  we 
owe  this  formula  so  promising  of  wonders,  not  only  denies 
that  it  can  be  appHed  practically,  but  also  brings  forward 
another  argument  that  casts  us  down  to  earth  again.  Sup- 
posing, he  explained,  it  were  possible  to  set  free  this  enormous 
store  of  energy,  then  we  should  only  arrive  at  an  age,  compared 
with  which  the  present  coal  age  would  have  to  be  called 
golden. 

And,  unfortimately,  we  find  ourselves  obliged  to  fall  in 
with  this  view,  which  is  based  in  the  wise  old  saw  fMrjBev  dyav, 
ne  quid  nimis,  nothing  in  excess.  AppHed  to  our  case,  this 
means  that  when  such  a  measure  of  power  is  set  free,  it  does 
not  serve  a  useful  purpose,  but  leads  to  destruction.  The 
process  of  burning,  which  we  used  as  an  illustration,  calls  up 
the  picture  of  an  oven  in  which  we  can  imagine  this  wholesale 
production  of  energy,  and  experience  tells  us  that  we  should 
not  heat  an  oven  with  dynamite. 

If  technical  developments  of  this  kind  were  to  come  about, 
the  energy  supply  would  probably  not  be  capable  of  regulation 
at  all.  It  makes  no  difference  if  we  say  that  we  only  want 
a  part  of  those  20  biUion  calories,  and  that  we  should  be  glad 
to  be  able  to  multiply  the  8000  calories  required  to-day  by 
100.  That  is  not  possible,  for  if  we  should  succeed  in  disin- 
tegrating the  atom,  it  seems  that  we  should  have  the  biUions 
of  calories  rushing  unchecked  on  us,  and  we  should  find  our- 
selves unable  to  cope  with  them,  nay,  perhaps  even  the  sohd 
ground,  on  which  we  move,  could  not  withstand  them» 
3 


84  EINSTEIN  THE  SEARCHER 

No  discovery  remains  a  monopoly  of  only  a  few  people. 
If  a  very  careful  scientist  should  really  succeed  in  producing 
a  practical  heating  or  driving  effect  from  the  atom,  then  any 
untrained  person  would  be  able  to  blow  up  a  whole  town 
by  means  of  only  a  minute  quantity  of  substance.  And  any 
suicidal  maniac  who  hated  his  fellows  and  wished  to  pulverize 
all  habitations  within  a  wide  range  would  only  have  to  con- 
ceive the  plan  to  carry  it  out  at  a  moment's  notice.  All  the 
bombardments  that  have  taken  place  ever  since  fire-arms 
were  invented  would  be  mere  child's  play  compared  with  the 
destruction  that  could  be  caused  by  two  buckets  of  coal. 

At  intervals  we  see  stars  Ught  up  in  the  heavens,  and 
then  become  extinguished  again  ;  from  these  we  infer  that 
world  catastrophes  have  occurred.  We  do  not  know  whether 
it  is  due  to  the  explosion  of  hydrogen  with  other  gases,  or  to 
colUsions  between  two  stellar  bodies.  There  is  still  room  for 
the  assumption  that,  immeasurably  far  away  in  yonder  regions 
of  celestial  space,  something  is  happening  which  a  malevolent 
inhabitant  of  our  earth,  who  has  discovered  the  secret  of 
smashing  the  atom,  might  here  repeat.  And  even  if  our 
imaginations  can  be  stretched  to  paint  the  blessings  of  this 
release  of  energy,  they  certainly  fail  to  conjure  up  visions 
of  the  disastrous  effects  which  would  result. 

Einstein  turned  to  a  page  in  a  learned  work  of  the  mathe- 
matical physicist  Weyl  of  Ziirich,  and  pointed  out  a  part  that 
dealt  with  such  an  appalling  liberation  of  energy.  It  seemed 
to  me  to  be  of  the  nature  of  a  fervent  prayer  that  Heaven 
preserve  us  from  such  explosive  forces  ever  being  let  loose 
on  mankind  ! 

Subject  to  present  impossibility,  it  is  possible  to  weave 
many  parallel  instances.  It  is  conceivable  that  by  some  yet 
undiscovered  process  alcohol  may  be  prepared  as  plentifully 
and  as  cheaply  as  ordinary  water.  This  would  end  the  short- 
age of  alcohol,  and  would  assure  delirium  tremens  for  hundreds 
of  thousands.  The  evil  would  far  outweigh  the  good,  although 
it  might  be  avoidable,  for  one  can,  even  if  with  great  difficulty, 
imagine  precautionary  measures. 

War  technique  might  lead  to  the  use  of  weapons  of  great 
range,  which  would  enable  a  small  number  of  adventurers  to 
conquer  a  Great  Power.    It  will  be  objected  :  this  will  hold 


BEYOND  OUR  POWER  85 

vice  versa,  too.  Nevertheless,  this  would  not  alter  the  fact 
that  such  long-range  weapons  would  probably  lead  to  the 
destruction  of  civiHzation.  Our  last  hope  of  an  escape  would 
be  in  a  superior  moral  outlook  of  future  generations,  which 
the  optimist  may  imagine  to  himself  as  the  force  majeure. 

There  are  apparently  only  two  inventions,  in  themselves 
triumphs  of  intellect,  against  which  one  would  have  no  defence. 
The  first  would  be  thought-reading  made  appHcable  to  all, 
and  with  which  Kant  has  dealt  imder  the  term  "  thinking 
aloud."  What  is  nowadays  a  rare  and  very  imperfect  tele- 
pathic "  turn  "  may  yet  be  generaHzed  and  perfected  in  a 
manner  which  Kant  supposed  not  impossible  on  some  distant 
planet.  The  association  and  converse  of  man  with  his  fellows 
would  not  stand  the  test  of  this  invention,  and  we  should  have 
to  be  angels  to  survive  it  even  for  a  day. 

The  second  invention  would  be  the  solution  of  this  md^- 
problem,  which  I  call  a  problem  only  because  I  fail  to  discover 
a  proper  term,  whereas  so  far  was  it  from  being  a  problem 
for  Einstein  that  it  was  only  in  my  presence  he  began  to 
reckon  it  out  in  figures  from  the  symboUc  formula.  To 
us  average  beings  a  Utopia  may  disclose  itself,  a  short 
frenzy  of  joy  followed  by  a  cold  douche  :  Einstein  stands 
above  it  as  the  pure  searcher,  who  is  interested  only  in  the 
scientific  fact,  and  who,  even  at  the  first  knowledge  of  it, 
preserves  its  essentially  theoretical  importance  from  attempts 
to  apply  it  practically.  If,  then,  another  wishes  to  hammer 
out  into  a  fantastic  gold-leaf  what  he  has  produced  as  a 
nttle  particle  of  gold  in  his  physical  investigations,  he  offers 
no  opposition  to  such  thought-experiments,  for  one  of  the 
deepest  traits  of  his  nature  is  tolerance. 

A.  Pfliiger,  one  of  the  best  quahfied  heralds  of  the 
new  doctrine,  has  touched  on  the  above  matter  in  his 
essay.  The  Principle  of  Relativity.  Einstein  praised  this 
pamphlet ;  I  mentioned  that  the  author  took  a  view  differ- 
ent from  that  of  Einstein,  of  the  possibiHty  of  making  ac- 
cessible the  mc'^.  In  discussing  the  practical  significance  of 
this  eventuaUty,  Pfliiger  says  :  "It  will  be  time  to  talk  of 
this  point  again  a  himdred  years  hence."  This  seems  a 
short  time-Hmit,  even  if  none  of  us  will  live  to  be  present  at 
the  discussion.    Einstein  smiled  at  this  pause  of  a  hundred 


36  EINSTEIN  THE  SEARCHER 

years,  and  merely  repeated,  "  A  very  good  essay !  "  It  is 
not  for  me  to  offer  contradictions  ;  and,  as  far  as  the  implied 
prognostication  is  concerned,  it  will  be  best  for  mankind 
if  it  should  prove  to  be  false.  If  the  optimum  is  unattainable, 
at  least  we  shall  be  spared  the  worst,  which  is  what  the  realiza- 
tion of  this  prophecy  would  inflict  on  us. 

Some  months  after  the  above  discussion  had  first  been 
put  to  paper,  the  world  was  confronted  by  a  new  scientific 
event.  The  EngUsh  physicist  Rutherford  had,  with  deliberate 
intention,  actually  succeeded  in  spUtting  up  the  atom. 
When  I  questioned  Einstein  on  the  possible  consequences  of 
this  experimental  achievement,  he  declared  with  his  usual 
frankness,  one  of  the  treasures  of  his  character,  that  he  had 
now  occasion  to  modify  somewhat  the  opinion  he  had  shortly 
before  expressed.  This  is  not  to  mean  that  he  now  considered 
the  practical  goal  of  getting  unlimited  supply  of  energy  as 
having  been  brought  within  the  realm  of  possibility.  He  gave 
it  as  his  view  that  we  are  now  entering  on  a  new  stage  of 
development,  which  may  perhaps  disclose  fresh  openings  for 
technical  science.  The  scientific  importance  of  these  new 
experiments  with  the  atom  was  certainly  to  be  considered  very 
great. 

In  Rutherford's  operations  the  atom  is  treated  as  if  he 
were  dealing  with  a  fortress  :  he  subjects  it  to  a  bombardment 
and  then  seeks  to  fire  into  the  breach.  The  fortress  is  still 
certainly  far  from  capitulating,  but  signs  of  disruption  have 
become  observable.  A  hail  of  bullets  caused  holes,  tears, 
and  splint erings. 

The  projectiles  hurled  by  Rutherford  are  alpha-particles 
shot  out  by  radium,  and  their  velocity  approaches  two-thirds 
that  of  light.  Owing  to  the  extreme  violence  of  the  impact, 
they  succeeded  in  doing  damage  to  certain  atoms  enclosed  in 
evacuated  glass  tubes.  It  was  shown  that  atoms  of  nitrogen 
had  been  disrupted.  It  is  still  unknown  what  quantities  of 
energy  are  released  in  this  process.  This  splitting  up  of  the 
atom  carried  out  with  intention  can,  indeed,  be  detected  only 
by  the  most  careful  investigations. 

As  far  as  practical  applications  are  concerned,  then,  we 
have  got  no  further,  although  we  have  renewed  grounds  for 
hope.     The  unit  of  measure,  as  it  were,  is  still  out  of  pro- 


BEYOND  OUR  POWER  87 

portion  to  the  material  to  be  cut.  For  the  forces  which 
Rutherford  had  to  use  to  attain  this  result  are  relatively  very 
considerable.  He  derived  them  from  a  gramme  of  radium, 
which  is  able  to  Uberate  several  milliard  calories,  whereas  the 
net  practical  result  in  Rutherford's  experiment  is  still  im- 
measurably small.  Nevertheless,  it  is  scientifically  estabUshed 
that  it  is  possible  to  split  up  atoms  of  one's  own  free  will, 
and  thus  the  fundamental  objection  raised  above  falls  to 
the  ground. 

There  is  also  another  reason  for  increased  hope.  It  seems 
feasible  that,  under  certain  conditions.  Nature  would  auto- 
matically continue  the  disruption  of  the  atom,  after  a  human 
being  had  intentionally  started  it,  as  in  the  analogous  case  of 
a  conflagration  which  extends,  although  it  may  have  started 
from  a  mere  spark. 

A  by-product  of  future  research  might  lead  to  the  trans- 
mutation of  lead  into  gold.  The  possibiUty  of  this  transforma- 
tion of  elements  is  subject  to  the  same  argmnents  as  those 
above  about  the  spUtting  up  of  the  atom  and  the  release  of 
great  quantities  of  energy.  The  path  of  decay  from  radium 
to  lead  lies  clearly  exposed  even  now,  but  it  is  very  question- 
able whether  mankind  will  finally  have  cause  to  offer  up  hymns 
of  thanksgiving  if  this  fine  from  lead  on  to  the  precious  metals 
should  be  continued,  for  it  would  cause  our  conception  of  the 
latter  to  be  shattered.  Gold  made  from  lead  would  not  give 
rise  to  an  increase  in  the  value  of  the  meaner  metal,  but  to  the 
utter  depreciation  of  gold,  and  hence  the  loss  of  the  standard 
of  value  that  has  been  vahd  since  the  beginning  of  our  civiUza- 
tion.  No  economist  would  be  possessed  of  a  sufficiently 
far-sighted  vision  to  be  able  to  measure  the  consequences  on 
the  world's  market  of  such  a  revolution  in  values. 

The  chief  product  would,  of  course,  be  the  gain  in  energy, 
and  we  must  bear  this  in  mind  when  we  give  ourselves  up  to 
our  speculations,  however  optimistic  or  catastrophic  they  may 
be.  The  impenetrable  barrier  "  impossible  "  no  longer  exists. 
Einstein's  wonderful  "  Open  Sesame,"  mass  times  the  square 
of  the  velocity  of  Hght,  is  thundering  at  the  portals. 

And  mankind  finds  a  new  meaning  in  the  old  saw  :  One 
should  never  say  never  ! 


CHAPTER  III 
VALHALLA 

Order  of  Distinction  and  Characteristics  of  Great  Discoverers. — Galilei 
and  Newton. — Forerunners  and  Priority. — Science  and  Religion. — Inherit- 
ance of  Talent. — A  Dynasty  of  Scholars. — Alexander  von  Humboldt  and 
Goethe. — Leonardo  da  Vinci. — Helmholtz. — Robert  Mayer  and  Diihring. — 
Gauss  and  Riemann. — Max  Planck. — Maxwell  and  Faraday. 

I  HAD  made  up  my  mind  to  question  Einstein  about  a 
number  of  famous  men,  not  concerning  mere  facts  of 
their  lives  and  works,  for  these  details  were  also  pro- 
curable elsewhere,  and,  moreover,  I  was  not  ignorant  of  them, 
but  what  attracted  me  particularly  was  to  try  to  discover  how 
the  greatness  of  one  might  be  compared  with  that  of  another. 
This  sometimes  helps  us  to  see  a  personaHty  in  a  different  Hght 
and  from  a  new  perspective,  which  leads  us  to  assign  to  him  a 
new  position  in  the  series  of  orders  of  merit. 

I  had  really  sketched  out  a  hst  for  this  purpose,  including 
a  great  number  of  glorious  names  from  the  annals  of  physics 
and  regions  just  beyond  :  a  table,  as  it  were,  from  which  one 
might  set  up  a  directory  for  Valhalla  !  It  seemed  to  me  a 
pleasing  thought  to  roam  through  this  hall  of  celebrities  in 
company  with  Einstein,  and  to  pause  at  the  pedestal  of  the 
busts  of  the  great,  who,  in  spite  of  their  number,  are  still  too 
few,  far  too  few,  in  comparison  with  the  far  too  many  who 
populate  the  earth  like  so  many  factory-produced  articles. 
If  we  set  to  work  to  draw  up  a  list  of  this  sort,  we  soon  find 
that  there  is  no  end  to  these  heroes  of  Valhalla,  and  we  are 
reminded  of  the  hall  of  fame  of  the  Northern  Saga,  of  the 
mythological  Valhalla,  whose  ceiling  was  so  high  that  the 
gable  was  invisible,  and  whose  extent  was  so  great  that  any- 
one wishing  to  enter  could  choose  from  five  hundred  and  forty 
entrances. 

In  reaUty  our  little  excursion  was  far  from  taking  these 
dimensions,  the  chief  reason  being  probably  that  we  had 


VALHALLA  39 

begun  at  Newton.  However  attractive  it  may  be  to  hear 
Einstein  talk  of  Newton,  a  disadvantage  arises  in  that  we 
find  it  hard  to  take  leave  of  his  bust  situated  at  the  main 
portal,  and  that  we  continually  revert  to  it  even  when  we 
call  to  mind  the  remaining  paths  free  for  our  choice  and 
stretching  out  of  sight. 

ReaUty,  even  figuratively,  offered  a  picture  which  differed 
considerably  from  the  measm-es  of  greatness  apportioned 
by  legendary  accounts.  In  Einstein's  workroom,  certainly, 
a  visitor  encounters  portraits,  not  busts,  and  it  would  be  rash 
to  speak  of  this  httle  collection  of  portraits  as  of  a  miniature 
museum.  No,  it  is  certainly  not  that,  for  its  catalogue  num- 
bers only  to  three.  But  here  they  act  as  a  trinity  with  a 
special  significance  under  the  gaze  of  Einstein,  who  looks  up 
to  them  with  reverence.  To  him  their  contribution  of  thought 
is  immeasurable  ;  Faraday,  Maxwell  with  his  rich  coils  of 
hair,  and  between  them,  Newton  with  his  flowing  wig,  repre- 
sented in  an  excellent  Enghsh  engraving,  whose  border  con- 
sists of  symbohc  insignias  encircUng  his  distinguished-looking 
countenance. 

According  to  Schopenhauer,  the  measure  of  reverence  that 
one  can  feel  is  a  measure  of  one's  own  intrinsic  value.  Tell 
me  how  much  respect  you  can  feel,  and  I  shall  tell  you  what 
is  your  worth.  It  is  certainly  not  necessary  to  emphasize 
this  quaUty  specially  in  the  case  of  Einstein,  for  there  are  other 
points  of  vantage  from  which  we  may  form  an  estimate  of 
his  excellence.  Nevertheless,  I  make  special  mention  of  the 
circumstance  to  give  an  indication  of  the  difference  between  a 
revolutionary  discoverer  and  revolutionary  pioneers  in  other 
fields.  It  is  particularly  noticeable  that  inborn  respect  is 
seldom  found  in  modernists  of  Art.  The  only  means  of  pro- 
paganda known  to  them  consists  in  a  passionate  demmciation 
of  what  has  been  developed  historically  by  gradual  and  patient 
effort ;  their  retrospect  consists  of  immitigated  contempt ; 
they  profess  to  be  disciples  only  of  what  is  most  recent,  re- 
maining confined  within  the  narrow  circle  surrounding  their 
own  ego.  The  horizon  of  the  discoverer  has  a  different  radius. 
He  takes  over  responsibiUty  for  the  future  by  never  ceasing  his 
offerings  at  the  altar  of  the  Past.    There  is  probably  no  dis- 


40  EINSTEIN  THE  SEARCHER 

coverer  who  is  devoid  of  this  characteristic,  but  I  should  like 
to  emphasize  that,  among  all  the  scientists  with  whom  I  am 
acquainted,  no  one  recognizes  the  merit  of  others  so  warmly 
as  Einstein.  He  becomes  carried  away  with  enthusiasm  when 
he  talks  of  great  men,  or  of  such  as  appear  great  to  him.  His 
Valhalla  is  not,  of  course,  the  same  as  that  favoured  by  Ency- 
clopaedias, and  many  a  one  whom  we  rank  as  a  Sirius  among 
men  is  to  be  found  lower  than  the  sixth  order  of  magnitude 
in  Einstein's  list.  Nevertheless,  the  number  of  selection  of 
constellations  is  no  mean  one,  and  the  reverence  that  was 
originally  inspired  by  reasoned  thought  has  become  infused 
in  his  temperament  and  become  a  part  of  his  emotional  self. 

One  need  only  mention  the  name  of  Newton — and  even 
this  is  scarcely  necessary,  for  Newton  seems  always  near  at 
hand ;  if  I  happen  to  start  with  Descartes  or  Pascal,  it  does 
not  take  long  before  we  arrive  at  Newton.     avBpa  /xot  eweirT) ! 

Once  we  began  with  Laplace  ;  and  it  seemed  almost  as  if  the 
"  Trait e  de  la  m^chanique  celeste  **  was  to  become  the  subject 
of  discussion.  But  Einstein  left  his  seat,  and,  taking  up  a 
position  in  front  of  his  series  of  portraits  on  the  wall,  he  medi- 
tatively passed  his  hand  through  his  hair,  and  declared  : 

**  In  my  opinion  the  greatest  creative  geniuses  are  Galilei 
and  Newton,  whom  I  regard  in  a  certain  sense  as  forming  a 
unity.  And  in  this  unity  Newton  is  he  who  has  achieved 
the  most  imposing  feat  in  the  realm  of  science.  These  two 
were  the  first  to  create  a  system  of  mechanics  founded  on  a 
few  laws  and  giving  a  general  theory  of  motions,  the  totaUty 
of  which  represents  the  events  of  our  world." 

Interrupting  his  remarks,  I  asked  :  "  Can  Gahlei's  funda- 
mental law  of  inertia  (Newton's  First  Law  of  Motion)  be 
said  to  be  a  law  deduced  from  experience  ?  My  reason  for 
asking  is  that  the  whole  of  natural  science  is  a  science  of  ex- 
perience, and  not  merely  something  based  on  speculation. 
It  might  easily  suggest  itself  to  one  that  an  elementary  law 
hke  that  of  Galilei  or  Newton  could  be  derived  from  our  every- 
day experience.  But,  if  this  is  the  case,  how  is  it  that  science 
had  to  wait  so  long  before  this  simple  fact  was  discovered  ? 
Experience  is  as  old  as  the  hills  ;  why  did  the  law  of  inertia 
not  make  its  appearance  at  the  very  beginning,  when  Nature 
was  first  subjected  to  inquiry  ?  " 


VALHALLA  41 

"By  no  means  !  "  replied  Einstein.  "  The  discovery  of 
the  law  of  rectilinear  motion  of  a  body  under  no  external 
influences  is  not  at  all  a  result  of  experience.  On  the  contrary  ! 
A  circle,  too,  is  a  simple  line  of  motion,  and  has  often  been 
proclaimed  as  such  by  predecessors  of  Newton,  for  example, 
by  Aristoteles.  It  required  the  enormous  power  of  abstrac- 
tion possessed  only  by  a  giant  of  reason  to  stabihze  rectilinear 
motion  as  the  fundamental  form." 

To  this  may  be  added  that  before  and  even  after  the  time 
of  GaUlei,  not  only  the  circle  but  also  other  non-rectilinear  lines 
have  been  regarded  even  by  serious  thinkers  as  the  primary 
lines  given  by  Nature  ;  these  thinkers  even  dared  to  apply 
their  curviHnear  views  to  explaining  world  phenomena  that 
could  be  made  clear  only  after  GaUlei's  abstraction  had  been 
accepted. 

I  asked  whether  the  theory  of  gravitation  was  already 
implicitly  contained  in  GaUlei's  Laws  of  FaUing  Bodies.  Ein- 
stein's answer  was  in  the  negative  :  the  gravitational  theory 
falls  entirely  to  the  credit  of  Newton,  and  the  greatness  of  this 
intellectual  achievement  remains  unimpaired  even  if  the  efforts 
of  certain  forerunners  are  recognized.  He  mentioned  Robert 
Hooke,  whom,  among  others,  Schopenhauer  sets  up  against 
Newton,  with  absolute  injustice  and  from  petty  feeUngs  of 
antipathy,  which  takes  its  origin  from  Schopenhauer's  un- 
mathematical  type  of  mind.  The  vast  difference  between 
Hooke *s  prehminary  attempts  at  explaining  gravitation,  and 
Newton's  monumental  structure,  was  beyond  his  power  of 
discernment. 

*  Schopenhauer  (vol.  ii.  of  the  Parerga)  uses  two  arguments 
to  discredit  Newton.  Firstly,  he  refers  to  two  original  works, 
both  of  which  he  misinterprets  ;  secondly,  he  undertakes  a 
psychological  analysis  of  Newton.  He  uses  psychological 
means,  which  would  be  about  equally  reasonable  as  appl5dng 
the  Integral  Calculus  to  proving  facts  of  Ethical  Psychology, 
and  he  arrives  at  the  conclusion  that  priority  in  discovering 
the  law  of  gravitation  is  due  to  some  one  else ;  Hooke  is  pictured 
as  having  been  treated  hke  Columbus  :  we  now  hear  of 
"  America,"  and  Hkewise  '*  Newton's  Gravitational  System  "  ! 

Schopenhauer  has,  however,  quite  forgotten  that  he  him- 
self, some  pages  earlier,  trumpeted  forth  Newton's  imperishable 


42  EINSTEIN  THE  SEARCHER 

fame  with  the  words :  "To  form  an  estimate  of  tlie  great 
value  of  the  gravitational  system  which  was  at  least  completed 
and  firmly  estabhshed  by  Newton,  we  must  remind  ourselves 
how  entirely  nonplussed  about  the  origin  of  the  motion  of 
celestial  bodies  thinkers  had  previously  been  for  thousands  of 
years."  That  bears  the  ring  of  truth.  Newton's  greatness 
can  be  grasped  only  if  thousands  of  years  are  used  as  a  measure. 
Whereas  Schopenhauer  argued  from  grounds  drawn  from 
psychology  and  the  principle  of  universal  knowledge,  his  anta- 
gonist Hegel,  who  was  still  more  vague  in  these  fields,  sought  to 
dispense  with  both  Newton  and  Kepler  by  calUng  to  his  aid 
the  so-called  pure  intuition  of  the  curved  Hne.  In  an  exposition 
of  truly  comical  prolixity,  such  as  would  have  dehghted  the 
hearts  of  schohasts,  he  proves  that  the  ellipse  must  represent 
the  fundamental  type  of  planetary  motion,  this  being  quite  in- 
dependent of  Newton's  laws,  Kepler's  observations,  and  result- 
ing mathematical  relationships.  And  Hegel  actually  succeeds, 
with  a  nebulous  verbosity  almost  stultifying  in  its  unmeaning- 
ness,  in  paraphrasing  Kepler's  second  law  in  his  own  fashion. 
It  reads  Uke  an  extract  from  some  carnival  publication  issued 
by  scientists  in  a  bibulous  mood  to  make  fun  of  themselves. 

But  these  extravagances,  too,  serve  to  add  lustre  to  Newton, 
for  his  genius  shines  out  most  brilUantly  when  it  is  a  question  of 
expressing  clearly,  and  without  assumptions,  a  phenomenon  of 
cosmic  motion.  Here  there  are  no  forerunners,  not  even  with 
regard  to  his  own  law  of  gravitation.  Newton  showed  with 
truly  triumphant  logic  that  Kepler's  second  law  belongs  to 
those  things  that  are  really  self-evident. 

This  law,  taken  alone,  offers  considerable  difficulties  to 
anyone  who  learns  of  it  for  the  first  time.  Every  planet 
describes  an  ellipse  ;  that  is  accepted  without  demur.  But  the 
uninitiated  will  possibly  or  even  probably  deduce  from  this 
that  the  planet  will  pass  over  equal  lengths  of  arc  in  equal 
times.  By  no  means,  says  Kepler ;  the  arcs  traversed  in  equal 
times  are  unequal.  But  if  we  connect  every  point  of  the 
elUptic  path  with  a  definite  point  within  the  curve  (the  focus 
of  the  ellipse)  by  means  of  straight  fines,  each  of  which  is  called 
a  radius  vector,  we  get  that  the  areas  swept  out  by  the  radius 
vector  in  equal  times  (and  not  the  arcs)  are  equally  great. 
Why  is  this  so  ?     This  cannot  be  understood  a  priori.     But 


VALHALLA  48 

one  might  argue  that  since  the  attraction  of  the  sun  is  the 
governing  force,  this  will  probably  have  something  to  do  with 
Newton*s  law  of  gravitation,  in  particular  with  the  inverse 
square  of  the  distance.  And  one  might  further  infer  that,  if 
a  different  principle  of  gravitation  existed,  Kepler's  law  would 
assume  a  new  form. 

A  fact  amazing  in  its  simplicity  here  comes  to  Ught. 
Newton  states  the  proposition :  "  According  to  whatever 
law  an  accelerating  force  acts  from  a  centre  on  a  body  moving 
freely,  the  radius  vector  will  always  sweep  out  equal  areas  in 
equal  lengths  of  time." 

Nothing  is  assumed  except  the  law  of  inertia  and  a  little 
elementary  mathematics,  namely,  the  theorem  that  triangles 
on  the  same  base  and  of  the  same  altitude  are  equal  in  area. 
The  form  in  which  this  theorem  occurs  in  Newton's  simple 
drawing  is  certainly  astonishing.  One  feels  that  there  in  a 
few  strokes  a  cosmic  problem  is  solved ;  the  impression  is 
ineffaceable. 

This  theorem  together  with  its  proof  is  contained  in 
Newton's  chief  work,  Philosophice  naturalis  principia  mathe- 
matica.  The  interfusion  of  philosophy  and  mathematics 
furnished  him  with  the  natural  principles  of  knowledge.* 

Einstein  made  some  illuminating  remarks  about  Newton's 
famous  phrase :  "  Hypotheses  non  fingo."  I  had  said  that 
Newton  must  have  been  aware  that  it  is  impossible  to  build 
up  a  science  entirely  free  from  hypotheses.  Even  geometry 
itself  has  arrived  at  that  critical  stage  at  which  Gauss  and 
Riemann  discovered  its  hypothetical  foundations. 

Einstein  repUed  :  "  Accentuate  the  words  correctly  and 
the  true  sense  will  reveal  itself  !  "  It  is  the  last  word  that  is 
to  be  stressed  and  not  the  first.  Newton  did  not  want  to  feel 
himself  free  from  hypotheses,  but  rather  from  the  assumption 
that  he  invented  them,  except  when  this  was  absolutely 
necessary.  Newton,  then,  wished  to  express  that  he  did  not 
go  further  back  in  his  analysis  of  causes  than  was  absolutely 
inevitable. 

Perhaps,  I  allowed  myself  to  interject,  a  more  violent 
suspicion  against  the  word  "  h3rpo theses  "  was  prevalent  with 
scholars  in  Newton's  time  than  now.  Newton's  emphatic 
defence  would  then  appear  a  shade  more  inteUigible      Or  did 


44  EINSTEIN  THE  SEARCHER 

he  cherish  the  belief  that  his  world-law  was  the  only  possible 
one  in  Nature  ? 

Einstein  again  referred  to  the  universality  of  Newton's 
genius,  sa3dng  that  Newton  was  doubtless  aware  of  the 
range  within  which  his  law  was  valid :  this  law  applies  to  the 
realm  of  observation  and  experience,  but  is  not  given  a  priori, 
no  more  than  GaUlei's  Law  of  Inertia.  It  is  certainly  con- 
ceivable that  beyond  the  domain  of  human  experience  there 
may  be  an  undiscoverable  universe  in  which  a  different  funda- 
mental law  holds,  and  one  which,  nevertheless,  does  not  contra- 
dict the  principle  of  sufficient  reason. 

The  antithesis  :  SimpHcity — Complexity,  led  the  conversa- 
tion into  a  short  bypath ;  it  arose  out  of  an  example  which 
I  quoted  and  that  I  shall  repeat  here  even  if  it  may  seem 
irrelevant. 

One  might  well  expect  that  just  as  for  attraction  there 
must  be  a  general  law  for  resistance  or  repulsion.  And  if 
attraction  occurs  according  to  the  inverse  square  of  the 
distance,  then  it  would  be  an  extremely  interesting  parallel  if 
a  similar  law  were  to  hold  for  repulsion  except  that  the  pro- 
portionaUty  were  direct  instead  of  inverse.  There  have 
actually  been  physicists  who  have  proclaimed  a  direct  square 
law  of  repulsion  ;  I  have  heard  it  in  lectures  myself.  The 
action  of  a  resisting  medium,  as,  for  example,  the  resistance  of 
the  air  to  the  flight  of  a  cannon-ball,  is  stated  to  be  proportional 
to  the  square  of  the  velocity  of  the  projectile. 

This  theorem  is  wrong.  If  it  were  correct,  and  verified  by 
experiment,  we  should  have  to  regard  it  as  being  presumably 
the  only  possible  and  directly  evident  form  of  the  law  of  re- 
pulsion or  resistance.  There  would,  at  least,  be  no  logical 
reason  for  contradicting  it. 

But  here  we  have  a  mixed  relationship,  as  Einstein  calls  it — 
that  is,  we  are  unable  to  express  an  exact  connexion  between 
the  velocity  of  a  body  in  flight  and  the  air  resistance. 

This  fallacious  assumption  by  no  means  proceeded  from 
illogical  reasoning,  and  it  seemed  to  rest  on  a  sound  physical 
basis.  For,  so  it  was  argued,  if  the  velocity  is  doubled,  there 
is  twice  as  much  air  to  be  displaced,  so  that  the  resistance  will 
be  four  times  as  great.  But  this  was  contradicted  outright  by 
experimental  evidence.     One  cannot  even  call  it  an  approxi- 


VALHALLA  45 

mate  law,  except  for  very  low  speeds.  For  greater  speeds 
we  find,  instead  of  a  quadratic  relation,  a  cubical  one,  or  one 
of  a  more  complex  nature.  Photographs  have  demonstrated 
that  the  resistance  experienced  by  a  projectile  in  flight  is  due 
to  the  excitation  of  a  powerful  central  wave,  to  the  friction 
between  the  air  and  the  surface  of  the  projectile,  and  to  eddies 
produced  behind  the  projectile — that  is,  to  various  conjoined 
factors,  each  of  which  follows  a  different  law,  and  such  that 
the  combined  effect  cannot  be  expressed  by  a  simple  formula 
at  all.  This  phenomenon  is  thus  very  complicated  and  offers 
almost  insuperable  difficulties  to  analysis.  A  beautiful 
remark  was  once  made,  which  characterizes  such  events  in 
Nature. 

During  a  conversation  with  Laplace,  Fresnel  said  that 
Nature  does  not  worry  about  analytical  difficulties.  There 
is  nothing  simpler  than  Newton's  Law  in  spite  of  the 
compUcated  nature  of  planetary  motions.  "  Nature  here 
despises  our  analytical  difficulties,*'  said  Fresnel ;  "  she  applies 
simple  means,  and  then  by  combining  them  produces  an  almost 
inextricable  net  of  confusion.  Simplicity  lies  concealed  in 
this  chaos,  and  it  is  only  for  us  to  discover  it  !  "  But  this 
simplicity  when  it  is  discovered  is  not  always  foimd  to  be 
expressible  in  simple  formulae,  not  must  it  be  forgotten  that 
even  the  ultimate  discoverable  simpHcity  points  to  certain 
hypothetical  assumptions. 

"  Hypotheses  non  fingo ! "  This  phrase  of  Newton's 
remains  true,  if  we  maintain  Einstein's  interpretation :  "  He 
did  not  wish  to  go  further  back  in  his  analysis  of  causes  than 
was  absolutely  inevitable."  It  interested  me  to  pursue  this 
line  of  thought  suggested  by  Einstein  still  further,  and  I 
discovered  that  these  words  of  Newton  had  actually  been 
falsely  accentuated  and  hence  misinterpreted  by  many 
authorities  on  science.  Even  Mill  and  the  great  scholar, 
WilHam  Whewell,  succumbed  to  this  misunderstanding. 
Credit  must  be  given  to  a  more  modem  scholar.  Professor 
Vaihinger  of  Halle,  for  being  sufficiently  keen  of  hearing  to 
detect  the  true  accentuation ;  and  now  that  Einstein  has 
corroborated  fully  this  explanation,  doubts  as  to  the  true 
sense  of  the  words  are  no  longer  to  be  feared. 

The  trend  of  our  talk  brought  us  to  a  discussion  of  the 


46  EINSTEIN  THE  SEARCHER 

conception,  "law  of  nature."  Einstein  recalled  Mach's 
remarks,  and  indicated  that  the  point  was  to  determine  how 
much  we  read  out  of  Nature  ;  and  these  observations  made  at 
least  one  thing  clear,  namely,  that  every  law  signifies  some 
hmitation  ;  in  the  case  of  human  laws,  expressed  in  the  civil 
and  penal  code,  the  hmitation  affects  the  will,  and  possible 
actions,  whereas  natural  laws  signify  the  Umitations  which  we, 
taught  by  experience,  prescribe  to  our  expectations.  Never- 
theless, the  conception  remains  elastic,  for  the  question  will 
always  intrude  itself  :  What  does  prescription  mean  ?  Who 
prescribes  ?  Kant  has  assigned  to  Man  the  foremost  position 
inasmuch  as  it  is  he  who  is  regarded  by  Kant  as  prescribing 
laws  to  Nature.  Bacon  of  Verulam  emphasizes  the  ambiguous 
point  of  view  by  asserting :  "  Natura  non  vincitur  nisi  parendo," 
Man  conquers  Nature  only  by  obeying  her,  that  is,  by  conform- 
ing to  her  immanent  norms.  Thus  the  laws  exist  without 
us,  and  we  have  only  to  discover  them.  When  they  have  been 
found,  Man  can  react  by  applying  them  to  subdue  Nature. 
Man  becomes  the  dictator  and  dictates  to  Nature  the  laws 
according  to  which  she  for  her  part  has  to  subjugate  mankind. 
Whether  we  adopt  the  one  view  or  the  other,  there  is  a  vicious 
circle,  from  which  there  is  no  escape.  A  law  is  a  creation  of 
intellect,  and  Mephisto's  words  remain  true  :  "In  the  end  we 
depend  on  the  creatures  of  our  own  making  !  " 

In  Newton's  soul  obedience  and  the  wish  to  obey  must 
have  been  pre-eminent  traits.  Is  he  not  reputed  to  have 
been  pious  and  strong  of  faith  ? 

Einstein  confirmed  this,  and,  raising  his  voice,  he  generahzed 
from  it,  saying  :  "In  every  true  searcher  of  Nature  there  is  a 
kind  of  religious  reverence  ;  for  he  finds  it  impossible  to 
imagine  that  he  is  the  first  to  have  thought  out  the  exceedingly 
dehcate  threads  that  connect  his  perceptions.  The  aspect 
of  knowledge  which  has  not  yet  been  laid  bare  gives  the  in- 
vestigator a  feeling  akin  to  that  experienced  by  a  child  who 
seeks  to  grasp  the  masterly  way  in  which  elders  manipulate 
things.'* 

This  explanation  imphed  a  personal  confession.  For  he 
had  spoken  of  the  childlike  longing  felt  by  all,  and  had  inter- 
preted the  subtle  intricacies  of  the  scientist's  ideas  in  par- 
ticular as  springing  from  a  rehgious  source.    Not  all  have 


VALHALLA  47 

confessed  this ;  we  know,  indeed,  that  the  convictions  of 
many  a  one  were  not  so.  Let  us  cling  to  the  fact  that  the 
greatest  in  the  realm  of  science — Newton,  Descartes,  Gauss, 
and  Helmholtz — were  pious,  although  their  faith  varied  in 
degree.  And  let  us  not  forget  that  the  most  bitter  opponent 
of  this  attitude  of  mind,  the  originator  of  "  Ecrasez  I'infame,*' 
j&nally  had  a  temple  built  bearing  the  inscription  :  "  Deo 
erexit  Voltaire." 

In  Newton  positivism  found  its  most  faithful  disciple,  and 
his  research  was  directly  affected  by  his  religious  attitude.  He, 
himself,  was  the  author  of  that  beautiful  thought :  *'  A  Umited 
measure  of  knowledge  takes  us  away  from  God  ;  an  increased 
measure  of  knowledge  takes  us  back  to  Him."  It  was  he  who 
considered  that  the  world-machine  that  he  had  disclosed  was 
not  sufficiently  stabilized  by  his  mathematical  law,  and  so  he 
enlisted  the  intermittent  help  of  an  assistant  for  the  Creator, 
Concursus  Dei,  to  attend  to  the  functionii^g  of  the  machine. 
Finally,  he  slipped  from  the  path  of  naive  faith  on  to  theo- 
logical bypaths  and  wrote  devout  essays  on  apocalyptic  matters. 
On  the  other  hand,  Descartes'  piety,  which  was  genuine  at  root, 
exhibited  suspicious  offshoots,  and  one  cannot  shake  off  the 
feeHng  that  he  was  smiUng  up  his  sleeve  when  he  was  making 
some  of  his  solemn  declarations.  He  was  a  master  of  com- 
promise, and  gave  due  expression  to  its  spirit,  which  F.  A. 
Lange  bluntly  stated  was  merely  a  veil  for  "  Cowardice 
towards  the  Church."  Voltaire,  an  apostle  of  Newton's 
system  of  natural  philosophy,  went  so  far  in  his  condemnation 
of  Descartes'  confession  of  faith  that  he  af&rmed  :  "  The 
Cartesian  doctrine  has  been  mainly  ii^strumental  in  persuading 
many  not  to  recognize  a  God.'* 

As  Einstein  had  called  special  attention  to  the  childHke 
nature  of  the  scientist's  root-impulse,  I  quoted  a  remark  of 
Newton  that  seemed  to  me  at  the  moment  to  be  a  confirma- 
tion of  Einstein's  attitude  : 

"  I  do  not  know  what  I  may  appear  to  the  world,  but 
to  myself  I  seem  to  have  been  only  Uke  a  boy  playing  on 
the  seashore,  and  diverting  myself  in  now  and  then  find- 
ing a  smoother  pebble  or  a  prettier  shell  than  ordinary, 
whilst  the  great  ocean  of  truth  lay  all  undiscovered  before 
me. 


48  EINSTEIN  THE  SEARCHER 

Are  we  not  to  regard  this  analogy  of  Newton's  as  being 
intended  to  convey  a  religious  meaning  ? 

**  There  is  no  objection  to  this,"  said  Einstein,  *'  although 
it  seems  to  me  more  probable  that,  in  saying  this,  Newton  set 
down  the  view  only  of  the  pure  investigator.  The  essential 
purpose  of  his  remarks  was  to  express  how  small  is  the  range 
of  the  attainable  compared  with  the  infinite  expanse  offered 
for  research." 

Through  some  unexpected  phrase  that  was  dropped,  the 
conversation  took  a  new  turn  at  this  point,  which  I  should 
not  Hke-4;o  withhold,  inasmuch  as  it  gave  rise  to  a  noteworthy 
observation  of  Einstein  about  the  nature  of  genius.  We  were 
talking  about  the  '*possibiUty  of  genius  for  science  being 
inherited  "  and  about  the  comparative  rareness  with  which 
it  occurs.  There  seems  to  have  been  only  one  case  of  a  real 
d5niasty  of  great  minds,  that  of  the  ten  BernouUis  who  were 
descended  of  a  line  of  mathematicians,  and  all  of  them  achieved 
important  results,  some  of  them  making  extraordinary  dis- 
coveries. Why  is  this  exception  unique  ?  In  other  examples 
we  do  not  get  beyond  three  or  four  names  in  the  same  family, 
even  if  we  take  Science  and  Art  conjointly.  There  were  two 
Plinys,  two  GaHleis,  two  Herschels,  two  Humboldts,  two 
Lippis,  two  Dumas,  several  Bachs,  Pisanos,  Robbias,  and 
Holbeins — the  net  result  is  very  poor,  even  if  we  count  similar 
names,  disregarding  the  fact  of  relationship  ;  there  is  no 
recognizable  dynasty  except  in  the  case  of  the  ten  BernouUis.* 
**  And  so,"  I  continued,  "  the  conclusion  seems  justified  that 
Nature  has  nothing  to  do  with  a  genealogy  of  talents,  and 
that,  if  we  happen  to  notice  manifestations  of  talent  in  one 
and  the  same  family,  this  is  a  mere  play  of  chance." 

Einstein,  however,  contradicted  this  emphatically  :  "In- 
herited talent  certainly  occurs  in  many  cases,  where  we  do  not 
observe  it,  for  genius  in  itself  and  the  possibiHty  of  genius 
being  apprehended  are  certainly  far  from  always  appearing  in 
conjunction.  There  are  only  insignificant  differences  between 
the  genius  that  expresses  itself  in  remarkable  achievements  and 

*  The  Roman  family  Cosmati  (of  the  thirteenth  century) ,  which  gave  us 
seven  splendid  representatives  of  architecture  andfmosaic  work,  hardly  comes 
into  consideration,  since  not  one  of  them  is  regarded  in  the  history  of  art  as 
a  real  genius. 


VALHALLA  49 

the  genius  that  is  latent.  At  a  certain  instant,  perhaps,  only 
some  impulse  was  wanting  for  the  latent  genius  to  burst  fo^h 
with  all  clearness  and  brilhance  ;  or,  perhaps,  it  required  only 
an  unusual  situation  in  the  development  of  science  to  call 
into  action  his  special  talents,  and  thus  it  remained  dormant, 
whereas  a  very  sHght  change  of  circumstances  would  have 
caused  them  to  assert  themselves  in  definite  results. 

"  In  passing  I  should  like  to  remark  that  you  just  now 
mentioned  the  two  Humboldts  ;  it  seems  to  me  that  Alexander 
von  Humboldt,  at  least,  is  not  to  be  counted  as  a  genius.  It 
has  struck  me  repeatedly  that  you  pronoimced  his  name  with 
particular  reverence " 

"  And  I  have  observed  equally  often.  Professor,  that  you 
made  a  sign  of  disapproval.  For  this  reason  slight  doubts 
have  gradually  been  rising  in  me.  But  it  is  dif&cult  to  get  free 
from  the  orders  of  greatness  that  one  has  recognized  for  de- 
cades. In  my  youth  people  spoke  of  *  a  Humboldt  *  just 
as  we  speak  of  '  a  Caesar  '  or  '  a  Michelangelo,'  to  denote 
some  pinnacle  of  unrivalled  height.  To  me  at  that  time 
Humboldt's  Kosmos  was  the  Bible  of  Natural  Science,  and 
probably  such  memories  have  a  certain  after-effect." 

"  That  is  easy  to  imderstand,"  said  Einstein.  "  But  we 
must  make  it  clear  to  ourselves  that  for  us  of  the  present  day 
Humboldt  scarcely  comes  into  consideration  when  we  direct 
our  gaze  on  to  the  great  seers.  Or,  let  us  say  more  clearly, 
he  does  not  belong  to  this  category.  I  certainly  grant  him 
his  immense  knowledge  and  his  admirable  faculty  of  getting 
into  touch  with  the  unity  of  Nature,  which  reminds  us  of 
Goethe." 

"  Yes  ;  this  feeling  for  the  uniformity  of  the  cosmos  had 
probably  persuaded  me  in  his  favour,"  I  answered,  "  and  I  am 
glad  that  you  draw  a  parallel  with  Goethe  in  this  respect.  It 
reminds  me  of  Heine's  story  :  If  God  had  created  the  whole 
world,  except  the  trees  and  the  birds,  and  had  said  to  Goethe  : 
*  My  dear  Goethe,  I  leave  it  to  you  to  complete  this  work,' 
Goethe  would  have  solved  the  problem  correctly  and  in  a  god- 
like manner — that  is,  he  would  have  painted  the  trees  green 
and  given  the  birds  feathers. 

"  Humboldt  could  equally  well  have  been  entrusted  with 
this  task.  But  various  objections  may  be  raised  against  such 
4 


50  EINSTEIN  THE  SEARCHER 

reflections  of  a  playful  poetic  character  .  .  .  one  objection 
being  that  Goethe's  own  knowledge  of  ornithology  was  ex- 
ceedingly Hmited.  Even  when  nearly  eighty  he  could  not 
distinguish  a  lark  from  a  yellow-hammer  or  a  sparrow  I  Is 
that  a  fact  ?" 

"  Fully  confirmed :  Eckermann  gives  a  detailed  report  of 
it  in  a  conversation  which  took  place  in  1827.  As  I  happened 
to  come  across  the  passage  only  yesterday,  I  can  quote  the 
exact  words  if  you  will  allow  me  :  '  Great  and  good  man/ 
thought  Eckermann,  *  who  hast  explored  Nature  as  few  have 
ever  done,  in  ornithology  thou  seemest  still  a  child ! '  " 

For  a  speculative  philosopher,  it  may  here  be  interposed, 
this  might  well  serve  as  the  starting-point  of  an  attractive 
investigation.  Goethe,  on  the  one  hand,  cannot  recognize  a 
lark,  but  would  have  been  able  to  grasp  the  Platonic  idea 
of  the  feathered  species,  even  if  there  had  been  no  such  things 
as  birds :  Humboldt,  on  the  other  hand,  would  perhaps  have 
been  able  to  create  the  revolving  planets,  if  Heaven  had  com- 
manded it ;  but  he  would  never  have  succeeded  in  becoming 
the  author  of  what  we  call  an  astronomical  achievement, 
such  as  that  of  Copernicus  or  of  Kepler. 

And  with  reference  to  certain  other  men  I  eUcited  from 
Einstein  utterances  that  reduced  somewhat  my  estimate  of 
their  importance. 

We  were  speaking  of  Leonardo  da  Vinci,  omitting  all 
reference  to  his  significance  in  the  world  of  Art — that  is,  only 
of  Leonardo  the  Scholar  and  the  Searcher.  Einstein  is  far 
from  disputing  his  place  in  the  Valhalla  of  great  minds,  but 
it  was  clear  that  he  wished  to  recommend  a  re-numbering  of 
my  Hst,  so  that  the  Italian  master  would  not  occupy  a  position 
in  just  the  first  rank. 

The  problem  of  Leonardo  excited  great  interest  in  me, 
and  it  deserves  the  consideration  of  every  one.  The  further 
the  examination  of  his  writings  advances,  the  more  does  this 
problem  resolve  itself  into  the  question  :  How  much  altogether 
does  modern  science  owe  to  Leonardo  ?  Nowadays  it  is 
declared  in  all  earnestness  that  he  was  a  painter  and  a  sculptor 
only  by  the  way,  that  his  chief  profession  was  that  of  an 
engineer,  and  that  he  was  the  greatest  engineer  of  all  times. 
This  has  in  turn  given  rise  to  the  opinion  that,  as  a  scientist. 


VALHALLA  51 

he  is  the  Ught  of  all  ages,  and  in  the  abundance  of  his  dis- 
coveries he  has  never  been  surpassed  before  or  after  his  own 
time. 

As  this  question  had  arisen  once  before,  I  had  come 
equipped  with  a  Httle  table  of  facts,  hastily  drawn  from  special 
works  to  which  I  had  access.  According  to  my  scheme, 
Leonardo  was  the  true  discoverer  and  author  of  the  following 
things  : 

Law  of  Conservation  of  Momentum. 

Law  of  Virtual  Velocities  (before  Ubaldi  and  Galilei). 

Wave  Theory  (before  Newton). 

Discovery   of   the   Circulation   of   the   Blood    (before 

Harvey). 
Laws  of  Friction  (before  Coulomb). 
Law    of    Pressure    for    connected    Tubes    containing 

Fluid  (before  Pascal). 
Action  of  Pressure  on  Fluids  (before  Stevin  and  GaUlei). 
Laws  of  FaUing  Bodies  (before  Gahlei). 
True  interpretation  of  the  twinkling  of  stars  (before 
Kepler,  who,  moreover,  did  not  succeed  in  finding 
the  real  explanation). 
Explanation  of  the  reflected  Ught  of  the  moon  (before 

Kepler). 
Principle  of  Least  Action  (before  Galilei). 
Introduction  of  the  plus  and  the  minus  signs  into 

calculations. 
Definition  of  kinetic  energy  from  mass  and  velocity. 
Theory  of  Combustion  (before  Bacon). 
Explanation  of  the  motion  of  the  sea  (before  Maury). 
Explanation  of  the  ascent  of  fluids  in  plants  (before 

Hales). 
Theory  of  Fossilization  (before  PaUssy). 
Added  to  these  there  are  a  great  number  of  inventions, 
in  particular  those  connected  with  problems  of  aviation,  such 
as  the  parachute  (before  Lenormand),  and  so  forth. 

This  Hst  aroused  great  distrust  in  Einstein  :  he  regarded 
it  as  the  outcome  of  an  inquisitive  search  for  sources,  excusable 
historically,  but  leading  to  misrepresentation.  We  are  falsely 
led  to  regard  slightly  related  beginnings,  vague  tracks,  hazy 
indications,  which  are  found,  as  evidences  of  a  real  insight. 


52  EINSTEIN  THE  SEARCHER 

which  disposes  us  to  "  elevate  one  above  all  others."  Hence 
a  mythological  process  results,  comparable  to  that  which,  in 
former  times,  thrust  all  conceivable  feats  of  strength  on  to 
one  Hercules. 

I  learned  that  recently  a  strong  reaction  has  asserted 
itself  in  scientific  circles  against  this  one-sided  hero-worship ; 
its  purpose  is  to  reduce  Leonardo's  merits  to  their  proper 
measure.  Einstein  made  it  quite  clear  that  he  was  certainly 
not  to  be  found  on  the  side  of  the  ultra-Leonardists. 

It  cannot  be  denied  that  the  latter  have  valuable  arguments 
to  support  their  case,  and  that  these  arguments  become 
multiplied  in  proportion  as  the  publication  of  Leonardo's 
writings  (in  the  Codex  Atlanticus,  etc.),  which  are  so  difficult  to 
decipher,  proceeds.  The  partisans  of  Leonardo  derive  consider- 
able support  in  many  points  from  recognized  authorities,  as 
in  the  case  of  Cantor,  the  author  of  the  monumental  history 
of  mathematics.  We  there  read :  "  The  greatest  Itahan 
painter  of  the  fifteenth  century  was  not  less  great  as  a  scientist. 
In  the  history  of  science  his  name  is  famous  and  his  achieve- 
ments are  extolled,  particularly  those  which  give  him  a  claim 
to  be  regarded  as  one  of  the  founders  of  Optics."  He  is 
placed  on  a  level  with  Regiomantus  as  one  of  the  chief  builders 
of  mathematics  of  that  time.  Nevertheless,  Cantor  raises 
certain  doubts  by  remarking  that  the  results  of  investigations 
made  up  to  the  present  do  not  prove  Leonardo  to  be  a  great 
mathematician.  On  another  page  he  is  proclaimed  simultane- 
ously with  Archimedes  and  Pappus  as  a  pioneer  of  the  doctrines 
of  the  centre  of  gravity. 

With  regard  to  the  main  points,  Leonardo's  priority  in 
the  case  of  the  Laws  of  FalUng  Bodies,  the  Theory  of  Wave- 
motion,  and  the  other  fundamental  principles  of  physics, 
Einstein  has  the  conviction  that  the  partisans  of  Leonardo 
are  either  mistaken  in  the  facts  or  that  they  overlook  fore- 
runners. In  the  case  of  these  principles,  above  all,  there  is 
always  some  predecessor,  and  it  is  almost  impossible  to  trace 
the  fine  of  discoveries  back  to  the  first  source.  Just  as  writers 
have  wished  to  deprive  Gahlei,  Kepler,  and  Newton  of  their 
laurels  in  favour  of  Leonardo,  so  the  same  might  be  done  with 
Copernicus. 

This  has  actually  been  attempted.     The  real  Copernicus, 


VALHALLA  53 

so  one  reads,  was  Hipparchus  of  Nicaea,  and  if  we  go  back 
still  further,  a  hundred  years  earlier,  two  thousand  years  ago, 
we  find  that  Aristarchus  of  Samos  taught  that  the  world 
rotated  about  its  own  axis  and  revolved  round  the  sun. 

And  we  need  not  even  stop  there,  in  Einstein's  opinion. 
For  it  is  open  to  conjecture  that  Aristarchus  in  his  turn  has 
drawn  on  Egyptian  sources.  This  retrogressive  investigation 
may  excite  the  interest  of  archaeologists,  and  in  particular 
cases  perhaps  lead  to  the  discovery  of  a  primary  claim  to 
authorship,  but  it  cannot  fail  to  excite  suspicion  against  the 
conscious  intention  of  conferring  all  the  honours  of  science 
on  an  individual  discoverer.  Leonardo's  superlative  con- 
structive genius  is  not  attacked  in  these  remarks,  and  there 
seems  no  reason  for  objecting  if  anyone  wishes  to  call  him 
the  most  ingenious  engineer  of  all  times. 

All  the  pressures  and  tensions  occurring  in  Nature  seemed 
to  be  repeated  in  him  as  "inner  virtues," »  an  expression 
borrowed  from  Helmholtz,  who  used  it  with  reference  to 
himself.  This  analogy  might  be  extended  by  saying  that, 
in  the  works  of  both,  Man  himself  with  his  organic  functions 
and  requirements  plays  an  important  role.  For  them  the 
abstract  was  a  means  of  arriving  at  what  was  perceptual, 
physiologically  useful,  and  stimulating  in  its  effect  on  life. 
Leonardo  started  out  from  Art,  and  throughout  the  realm 
of  mechanics  and  machines  he  remained  an  artist  in  method. 
Helmholtz  set  out  from  the  medical  side  of  physiology  and 
transferred  the  valuations  of  beauty  derived  from  the  senses 
to  his  pictures  of  mechanical  relationships.  The  Hfe-work 
of  each  has  an  aesthetic  colouring,  Leonardo's  being  of  a 
gloomy  hue,  that  of  Helmholtz  exhibiting  brighter  and  happier 
tints.  Common  to  both  is  an  almost  inconceivable  versatility 
and  an  inexhaustible  produjctivity. 

Whenever  Einstein  talks  of  Helmholtz  he  begins  in  warm 
terms  of  appreciation,  which  tend  to  become  cooler  in  the 
course  of  the  conversation.  I  cannot  quote  his  exact  words, 
and  as  I  cannot  thus  give  a  complete  account  for  which  full 
responsibility  may  be  taken,  it  may  be  allowable  to  offer  a 
few  important  fragments  that  I  have  gathered. 

Judged  by  the  average  of  his  accomplishments,  Helmholtz 
is  regarded  by  Einstein  as  an  imposing  figure  whose  fame  in 


54  EINSTEIN  THE  SEARCHER 

later  times  is  assured  ;  Helmholtz  himself  tasted  of  this  im- 
mortahty  while  still  alive.  But  when  efforts  are  made  to  rank 
him  with  great  thinkers  of  the  calibre  of  Newton,  Einstein 
considers  that  this  estimate  cannot  be  fully  borne  out.  In 
spite  of  all  the  excellence,  subtlety,  and  effectiveness  of  Helm- 
holtz's  astoundingly  varied  inspirations,  Einstein  seems  to  fail 
to  discover  in  him  the  source  of  a  really  great  intellectual 
achievement. 

At  a  Science  Congress  held  in  Paris  in  1867,  at  which  Helm- 
holtz was  present,  a  colleague  of  his  was  greeted  with  unanimous 
applause  when  he  toasted  him  with  the  words  :  "  L'ophthal- 
mologie  ^tait  dans  les  tenebres, — Dieu  parla,  que  Helmholtz 
naquit — Et  la  lumiere  etait  faite ! "  It  was  an  almost  exact 
paraphrase  of  the  homage  which  Pope  once  addressed  to 
Newton.  At  that  time  the  words  of  the  toast  were  re-echoed 
throughout  the  world  ;  ophthalmology  was  enlarged  to  science 
generally,  and  the  apotheosis  was  applied  universally.  Du 
Bois-Reymond  declared  that  no  other  nation  had  in  its  scientific 
literature  a  book  that  could  be  compared  with  Helmholtz's 
works  on  Physiological  Optics  and  on  Sensations  of  Tone. 
Helmholtz  was  regarded  as  a  god,  and  there  are  not  a  few  to 
whom  he  still  appears  crowned  with  this  divine  halo. 

A  shrill  voice  pierced  the  serene  atmosphere,  attacking  one 
of  his  main  achievements.  The  dissentient  was  Eugen  Diihring, 
to  whose  essay  on  the  Principles  of  Mechanics  a  coveted 
prize  was  awarded,  a  fact  which  seemed  to  stamp  him  as  being 
specially  authorized  to  be  a  judge  of  pre-eminent  achievements 
in  this  sphere.  Diihring's  aim  was  to  dislodge  one  of  the  funda- 
mental supports  of  Helmholtz's  reputation  by  attacking  his 
"  Law  of  the  Conservation  of  Energy."  If  this  assault 
proved  successful,  the  god  would  lie  shattered  at  his  own 
pedestal. 

Diihring,  indeed,  used  every  means  to  bespatter  his  fair 
name  in  science  ;  and  it  is  hardly  necessary  to  remark  that 
Einstein  abhors  this  kind  of  polemic.  What  is  more,  he  re- 
gards it  as  a  pathological  symptom,  and  has  only  a  smile  of 
disdain  for  many  of  Diihring's  pithy  sayings.  He  regards 
them  as  documents  of  unconscious  humour  to  be  preserved 
in  the  archives  of  science  as  warnings  against  future  repetitions 
of  such  methods. 


VALHALLA  55 

Diihring  belonged  also  to  those  who  wished  to  exalt  one 
above  all  others.  He  raised  an  altar  to  Robert  Mayer,  and 
offered  up  sanguinary  sacrifices.  Accustomed  to  doing  his 
work  thoroughly,  he  did  not  stop  at  Helmholtz  in  choosing 
his  victims.  No  hecatomb  seemed  to  him  too  great  to  do 
honour  to  the  discoverer  of  the  Mechanical  Equivalent  of 
Heat,  and  so  his  next  prey  was  Gauss  and  Riemann. 

Gauss  and  Riemann !  Each  was  a  giant  in  Einstein's  opinion. 
He  knew  well  that  this  raging  Ajax  had  also  made  an  assault 
against  them,  but  he  had  no  longer  a  clear  recollection  of  the 
detailed  circumstances  ;  as  the  references  were  near  at  hand, 
he  allowed  me  to  repeat  a  few  lines  of  this  tragi-comedy. 

Helmholtz,  according  to  Diihring  (who  also  calls  him 
"  Helmklotz  "),  has  done  no  more  than  distort  Mayer's  funda- 
mental mechanical  idea,  and  interpret  it  falsely.  By  "  philo- 
sophizing "  over  it,  he  has  completely  spoilt  it,  and  rendered 
it  absurd.  It  was  the  greatest  of  all  humihations  practised 
on  Mayer  that  his  name  had  been  coupled  with  that  of  one 
whom  he  had  easily  out-distanced,  and  whose  clumsy  attempts 
at  being  a  physicist  were  even  worse  than  those  by  which  he 
sought  to  establish  himself  as  a  philosopher. 

The  offences  of  Gauss  and  Riemann  against  Mayer  are 
shrouded  in  darkness.  But  there  was  another  would-be 
scientist,  Justus  von  Liebig,  who,  being  opposed  to  Mayer, 
aroused  the  suspicions  of  Diihring,  particularly  as  he  had  used 
his  *'  brazen-tongue  "  to  defend  the  two  renowned  mathe- 
maticians. After  he,  and  Clausius  too,  had  been  brought  to 
earth,  Diihring  launched  out  against  the  giants  of  Gottingen. 
In  the  chapter  on  Gauss  and  "  Gauss- worship,"  we  read : 
"  His  megalomania  rendered  it  impossible  for  him  to  take 
exception  to  any  tricks  that  the  deficient  parts  of  his  own 
brain  played  on  him,  particularly  in  the  realm  of  geometry. 
Thus  he  arrived  at  a  pretentiously  mystical  denial  of  EucUd's 
axioms  and  theorems,  and  proceeded  to  set  up  the  founda- 
tions of  an  apocalyptic  geometry  not  only  of  nonsense  but  of 
absolute  stupidity.  .  .  .  They  are  abortive  products  of  the 
deranged  mind  of  a  mathematical  professor,  whose  mania  for 
greatness  proclaims  them  as  new  and  superhuman  truths  !  .  .  . 
The  mathematical  delusions  and  deranged  ideas  in  question 
are  the  fruits  of  a  veritable  paranoia  geometrica.*' 

/ 


56  EINSTEIN  THE  SEARCHER 

After  Herostratus  had  burnt  to  ashes  the  consecrated 
temple,  the  Ionian  cities  issued  a  proclamation  that  his  name 
was  to  be  condemned  to  perpetual  oblivion  !  The  iconoclast 
Diihring  is  immortalized,  for,  apart  from  the  charge  of  arson, 
he  is  notable  in  himself.  In  his  case  we  found  ourselves  con- 
fronted with  unfathomable  problems  of  a  scholar's  complex 
nature,  problems  which  even  a  searcher  like  Einstein  failed  to 
solve.  The  simplest  solution  would  be  to  turn  the  tables  and 
to  apply  the  term  "  paranoia  "  as  a  criticism  to  the  book  on 
Robert  Mayer,  and  thus  demolish  it.  But  this  will  not  do, 
for  if  we  merely  pass  over  the  pages  of  distorted  thought, 
we  are  still  left  with  a  considerable  quantity  of  valuable 
material. 

Does  Diihring,  after  all,  himself  deserve  a  place  in  our 
Valhalla?  The  question  seems  monstrous,  and  yet  cannot 
be  directly  answered  in  the  negative.  The  individual  is  to 
be  judged  according  to  his  greatest  achievement,  and  not 
according  to  his  aberrations.  The  works  of  Aristotle  teem 
with  nonsensical  utterances,  and  Leonardo's  Bestiarius  is  an 
orgy  of  abstruse  concoctions.  If  Diihring  had  written  nothing 
beyond  his  studies  of  personalities  ranging  from  Archimedes 
to  Lagrange,  the  portals  would  yet  have  been  open  to  him. 
Even  in  his  eulogy  of  Robert  Mayer,  which  is  besmirched 
with  unseemly  remarks,  he  displays  at  least  the  courage  of  his 
convictions. 

The  attempt  at  a  comparison  between  Robert  Mayer  and 
Helmholtz  is  doomed  to  failure  even  when  considered  dis- 
passionately, inasmuch  as  the  disturbing  factor  of  priority  here 
intrudes  itself.  The  definite  fixing  of  the  Law  of  Energy  is 
certainly  to  the  credit  of  Helmholtz,  but  perhaps  he  would  have 
gained  by  laying  more  stress  on  the  discovery  of  it  five  years 
earlier  by  the  doctor  in  Heilbronn.  And  again,  this  would 
not  have  been  final,  for  the  in  variance  of  the  sum  of  energy 
during  mechanical  actions  was  known  even  by  Huyghens. 
The  Heilbronn  doctor  performed  one  act  of  genius  in  his  Hfe, 
whereas  Helmholtz  during  his  whole  Hfe  moved  asymptotically 
to  the  Une  of  genius  without  ever  reaching  it.  If  my  inter- 
pretation of  Einstein's  opinion  is  correct,  Helmholtz  is  to  be 
credited  with  having  the  splendour  of  an  overpowering  gift 
for  research  predominant  in  his  nature,  but  is  not  necessarily 


VALHALLA  57 

to  be  given  a  seat  among  the  most  illustrious  of  his  branch  of 
science.  Einstein  wishes  to  preserve  a  certain  hne  of  demarca- 
tion between  this  type  and  not  only  the  Titans  of  the  past, 
but  also  those  of  the  present.  When  he  speaks  of  the  latter, 
his  tone  becomes  warmer.  He  does  not  need  circuitous 
expressions,  each  syllable  rings  with  praise.  He  has  in 
mind,  above  all,  Hendrik  Antoon  Lorentz  in  Leyden,  Max 
Planck,  and  Niels  Bohr  ;  we  then  see  that  he  feels  Valhalla 
about  him. 

The  reason  that  I  have  tried  to  maintain  the  metaphor  of 
a  Temple  of  Fame  is  due  to  an  echo  of  Einstein's  own  words 
at  a  celebration  held  in  honour  of  the  sixtieth  birthday  of 
the  physicist  Planck  in  the  May  of  1918.  This  speech  created 
the  impression  of  a  happy  harmony  resulting  from  a  fusion 
of  two  melodies,  one  springing  from  the  intellect,  the  other 
rising  from  the  heart.  We  were  standing  as  at  the  Propylons 
with  a  new  HeracHtus  uttering  the  cry  :  Introite,  nam  et  hie 
dii  sunt  ! 

I  should  like  to  give  the  gist  of  this  beautiful  address  in 
an  extract  uninterrupted  by  commentaries. 

"  The  Temple  of  Science  " — so  Einstein  began — "  is  a 
complex  structure  of  many  parts.  Not  only  are  the  inmates 
diverse  in  nature,  but  so  also  are  the  inner  forces  that  they 
have  introduced  into  the  temple.  Many  a  one  among  them 
is  engaged  in  Science  with  a  happy  feeUng  of  a  superior  mind, 
and  finds  Science  the  sport  which  is  congenial  to  him,  and 
which  is  to  give  him  an  outlet  for  his  strong  Ufe-forces,  and  to 
bring  him  the  reahzation  of  his  ambitions.  There  are,  indeed, 
many,  too,  who  offer  up  their  sacrifice  of  brain-matter  only 
in  the  cause  of  useful  achievements.  If  now  an  angel  of  heaven 
were  to  come  and  expel  all  from  the  temple  who  belonged  to 
these  two  categories,  a  considerable  reduction  would  result, 
but  there  would  still  remain  within  the  temple  men  of  present 
and  former  times  :  among  these  we  count  our  Planck,  and 
that  is  why  he  has  our  warm  affection. 

' '  I  know  full  well  that,  in  doing  this,  we  have  hght-heartedly 
caused  many  to  be  driven  out  who  contributed  much  to  the 
building  of  the  temple  ;  in  many  cases  our  angel  would  find 
a  decision  difl&cult.  .  .  .  But  let  us  fix  our  gaze  on  those 


58  EINSTEIN  THE  SEARCHER 

who  find  full  favour  with  him  !     Most  of  them  are  peculiar, 
reserved,  and  lonely  men,  who,  in  spite  of  what  they  have 
in  common,  are  really  less  alike  than  those  who  have  been 
expelled.     What  led  them  into  the  temple  ?  ...  In  the  first 
place,  I  agree  with  Schopenhauer  that  one  of  the  most  powerful 
motives  that  attract  people  to  Science  and  Art  is  the  longing 
to  escape  from  everyday  life  with  its  painful  coarseness  and 
unconsoling  barrenness,  and  to  break  the  fetters  of  their  own 
ever-changing  desires.     It  drives  those  of  keener  sensibiUty 
out  of  their  personal  existence  into  the  world  of  objective 
perception  and  understanding.     This  motive  force  is  similar 
to  the  longing  which  makes  the  city-dweller  leave  his  noisy, 
confused  surroundings  and  draws  him  with  irresistible  force  to 
restful  Alpine  heights,  where  his  gaze  covers  the  wide  expanse 
lying  peacefully  before  him  on  all  sides,  and  softly  passes 
over  the  motionless  outhnes  that  seem  created  for  all  eternity. 
Associated  with  this  negative  motive  is  a  positive  one,  by 
virtue  of  which  Man  seeks  to  form  a  simpUfied  synoptical 
view  of  the  world  in  a  manner  conformable  to  his  own  nature, 
in  order  to  overcome  the  world  of  experience  by  replacing  it, 
to  a  certain  degree,  by  this  picture.     This  is  what  the  painter 
does,  as  also  the  poet,  the  speculative  philosopher,  and  the 
research  scientist,  each  in  his  own  way.     He  transfers  the 
centre  of  his  emotional  existence  into  this  picture,  in  order 
to  find  a  sure  haven  of  peace,  one  such  as  is  not  offered  in  the 
narrow  limits  of  turbulent  personal  experience. 

"  What  position  does  the  world-picture  of  the  theoretical 
physicist  occupy  among  all  those  that  are  possible  ?  He 
demands  the  greatest  rigour  and  accuracy  in  his  representation, 
such  as  can  be  gained  only  by  using  the  language  of  mathe- 
matics. But  for  this  very  reason  the  physicist  has  to  be  more 
modest  than  others  in  his  choice  of  material,  and  must  confine 
himself  to  the  simplest  events  of  the  empirical  world,  since 
all  the  more  complex  events  cannot  be  traced  by  the  human 
mind  with  that  refined  exactness  and  logical  sequence  which 
the  physicist  demands.  ...  Is  the  result  of  such  a  restricted 
effort  worthy  of  the  proud  name  '  world-picture  '  ? 

"  I  beheve  this  distinction  is  well  deserved,  for  the  most 
general  laws  on  which  the  system  of  ideas  set  up  by  theoretical 
physics  is  founded  claim  to  be  vahd  for  every  kind  of  natural 


VALHALLA  59 

phenomenon.  From  them  it  should  be  possible  by  means  of 
pure  deduction  to  find  the  picture,  that  is,  the  theory,  of  every 
natural  process,  including  those  of  living  organism,  provided 
that  this  process  of  deduction  does  not  exceed  the  powers 
of  human  thought.  Thus  there  is  no  fundamental  reason 
why  the  physical  picture  of  the  world  should  fall  short  of 
perfection.  .  .  . 

"  Evolution  has  shown  that  among  all  conceivable  theor- 
etical constructions  there  is  at  each  period  one  which  shows 
itself  to  be  superior  to  all  others,  and  that  the  world  of 
perception  determines  in  practice  the  theoretical  system, 
although  there  is  no  logical  f road  from  perception  to  the 
axioms  of  the  theory,  but  rather  that  we  are  led  towards 
the  latter  by  our  intuition,  which  establishes  contact  with 
experience.  .  .  . 

**  The  longing  to  discover  the  pre-established  harmony  recog- 
nized by  Leibniz  is  the  source  of  the  inexhaustible  patience 
with  which  we  see  Planck  devoting  himself  to  the  general 
problems  of  our  science,  refusing  to  allow  himself  to  be  dis- 
tracted by  more  grateful  and  more  easily  attainable  objects.  .  .  . 
The  emotional  condition  which  fits  him  for  his  task  is  akin 
to  that  of  a  devotee  or  a  lover ;  his  daily  striving  is  not  the 
result  of  a  definite  purpose  or  a  programme  of  i  action,  but 
of  a  direct  need.  .  .  .  May  his  love  for  Science  grace  his 
future  course  of  Ufe,  and  lead  him  to  a  solution  of  that  all- 
important  problem  of  the  day  which  he  himself  propounded, 
and  to  an  understanding  of  which  he  has  contributed  so 
much !  May  he  succeed  in  combining  the  Quantum  Theory 
with  Electrodynamics  and  Mechanics  in  a  logically  complete 
system  !  ** 

'*  What  grips  me  most  in  your  address,"  I  said,  "  is  that 
it  simultaneously  surveys  the  whole  horizon  of  science  in 
every  direction,  and  traces  back  the  longing  for  knowledge 
to  its  root  in  emotion.  When  your  speech  was  concluded, 
I  regretted  only  one  thing — that  it  had  ended  so  soon. 
Fortunate  is  he  who  may  study  the  text." 

"  Do  you  attach  any  importance  to  it  ?  "  asked  Einstein ; 
"  then  accept  this  manuscript."  It  is  due  to  this  act  of 
generosity  that  I  have  been  able  to  adorn  the  foregoing  de- 


60  EINSTEIN  THE  SEARCHER 

scription  of  the  excursion  into  Valhalla  with  such  a  valuable 
supplement. 

The  conversation  had  begun  with  the  brilliant  constella- 
tion Galilei-Newton,  and  near  the  end  inclined  again  towards 
the  consideration  of  a  double-star :  the  names  of  Faraday 
and  Maxwell  presented  themselves. 

"  Both  pairs,"  Einstein  declared,  "  are  of  the  same  magni- 
tude. I  regard  them  as  fundamentally  equal  in  their  services 
in  the  onward  march  of  knowledge." 

*'  Should  we  not  have  to  add  Heinrich  Hertz  as  a  third 
in  this  bond  ?  This  assistant  of  Helmholtz  is  surely  regarded 
as  one  of  the  founders  of  the  Electromagnetic  Theory  of  Light, 
and  we  often  hear  their  names  coupled,  as  in  the  case  of  the 
Maxwell- Hertz  equations." 

*'  Doubtless,"  repHed  Einstein,  "  Hertz,  who  is  often 
mentioned  together  with  Maxwell,  has  an  important  rank 
and  must  be  placed  very  high  in  the  world  of  experimental 
physics,  yet,  as  regards  the  influence  of  his  scientific  personaUty, 
he  cannot  be  classed  with  the  others  we  have  named.  Let 
us,  then,  confine  ourselves  to  the  twin  geniuses  Faraday  and 
Maxwell,  whose  intellectual  achievement  may  be  summarized 
in  a  few  words.  Classical  mechanics  referred  all  phenomena, 
electrical  as  well  as  mechanical,  to  the  direct  action  of  particles 
on  one  another,  irrespective  of  their  distances  from  one 
another.  The  simplest  law  of  this  kind  is  Newton's  expres- 
sion :  '  Attraction  equals  Mass  times  Mass  divided  by  the 
square  of  the  distance.'  In  contradistinction  to  this,  Faraday 
and  Maxwell  have  introduced  an  entirely  new  kind  of  physical 
realities,  nsLmely,  fields  of  force.  The  introduction  of  these  new 
realities  gives  us  the  enormous  advantage  that,  in  the  first 
place,  the  conception  of  action  at  a  distance,  which  is  contrary 
to  our  everyday  experience,  is  made  unnecessary,  inasmuch 
as  the  fields  are  superimposed  in  space  from  point  to  point 
without  a  break ;  in  the  second  place,  the  laws  for  the  field, 
especially  in  the  case  of  electricity,  assume  a  much  simpler 
form  than  if  no  field  be  assumed,  and  only  masses  and  motions 
be  regarded  as  realities." 

He  enlarged  still  further  on  the  subject  of  fields,  and 
while  he  was  describing  the   technical   details,   I  saw  him 


VALHALLA  61 

metaphorically  enveloped  in  a  magnetic  field  of  force.  Here, 
too,  an  influence,  transmitted  through  space  from  point  to 
point,  made  itself  felt,  and  there  could  be  no  question  of 
action  "  at  a  distance  "  inasmuch  as  the  effective  source  was 
so  near  at  hand.  His  gaze,  as  if  drawn  magnetically,  passed 
along  the  wall  of  the  room  and  fixed  affectionately  on  Maxwell 
and  Faraday. 


CHAPTER  IV 
EDUCATION 

School  Curricula  and  Reform  of  Teaching. — Value  of  Language  Study. 
— Economy  of  Time. — Practice  in  Manual  Work. — Picturesque  Illustrations. 
— Art  of  Lecturing. — Selection  of  Talents  by  Means  of  Examinations. — 
Women  Students. — Social  Diflficulties. — Necessity  as  Instructress. 

OUR  conversation  turned  towards  a  series  of  paedagogic 
questions,  in  which  Einstein  is  deeply  interested. 
For  he  himself  is  actively  engaged  in  teaching,  and 
never  disguises  the  pleasure  which  he  derives  from  imparting 
instruction.  Without  doubt  he  has  a  gift  of  making  his  spoken 
words  react  on  wide  circles  anxious  to  be  instructed,  composed 
not  only  of  University  students,  but  of  many  others  quite  outside 
this  category.  When,  recently,  popular  lectures  on  a  large 
scale  were  instituted,  he  was  one  of  the  first  to  offer  his  services 
in  this  sound  undertaking.  He  lectured  to  people  of  the 
working  class,  who  could  not  be  assumed  to  have  any  pre- 
liminary information  on  the  subject,  and  he  succeeded  in 
presenting  his  lectures  so  that  even  the  less  trained  minds  could 
easily  follow  his  argument. 

His  attitude  towards  general  questions  of  school  education 
is,  of  course,  conditioned  by  his  own  personahty  and  his  own 
work  in  the  past.  His  first  care  is  that  a  young  person  should 
get  an  insight  into  the  relationship  underlying  natural  pheno- 
mena, that  is,  that  the  curricula  should  be  mapped  out  so  that 
a  knowledge  of  facts  is  the  predominating  aim. 

"  My  wish,"  Einstein  declared  to  me,  "  is  far  removed  from 
the  desire  to  eliminate  altogether  the  fundamental  features  of 
the  old  grammar  schools,  with  their  preference  for  Latin,  by 
making  over-hasty  reforms,  but  I  am  just  as  Uttle  inclined 
to  wax  enthusiastic  about  the  so-called  humanistic  schools. 
Certain  recollections  of  my  own  school  life  sufi&ce  to  prevent 
this,  and  still  more,  a  certain  presentiment  of  the  educational 
problems  of  the  future." — "  To  speak  quite  candidly,"  he 


EDUCATION  68 

said,  "  in  my  opinion  the  educative  value  of  languages  is,  in 
general,  much  over-estimated." 

I  took  the  liberty  of  quoting  a  saying  that  is  still  regarded  as 
irrefutable  by  certain  scholars.  It  was  Charles  V  who  said : 
**  Each  additional  acquired  language  represents  an  additional 
personaUty '' ;  and  to  suggest  the  root  of  language  formation  he 
said  it  in  Latin  :  "  Quot  Hnguas  quis  callet,  tot  homines  valet/' 
This  saying  has  been  handed  down  through  the  ages  in  German 
in  the  form  :  "  Soviel  Sprachen,  soviel  Sinnen  "  (An  added 
language  means  an  added  sense). 

Einstein  repHed :  "I  doubt  whether  this  aphorism  is 
generally  vahd,  for  I  beheve  that  it  would  at  no  time  have 
stood  a  real  test.  All  experience  contradicts  it.  Otherwise 
we  should  be  compelled  to  assign  the  highest  positions  among 
intellectual  beings  to  linguistic  athletes  Uke  Mithridates, 
Mezzofanti,  and  similar  persons.  The  exact  opposite,  indeed, 
may  be  proved,  namely,  that  in  the  case  of  the  strongest  per- 
sonahties,  and  of  those  who  have  contributed  most  to  pro- 
gress, the  multiplicity  of  their  senses  in  no  wise  depended  on  a 
comprehensive  knowledge  of  languages,  but  rather  that  they 
avoided  burdening  their  minds  with  things  that  made  excessive 
claims  on  their  memories.*' 

"  Certainly,"  said  I,  "it  may  be  admitted  that  this  gives 
rise  to  exaggeration  in  some  cases,  and  that  the  linguistic  sort 
of  sport  practised  by  many  a  scholar  degenerates  to  a  mere 
display  of  knowledge.  An  intellectual  achievement  of  lasting 
merit  has  very  rarely  or  never  been  the  result  of  a  super- 
abundance of  acquired  Unguistic  knowledge.  An  instance 
occurs  to  me  at  this  moment.  Nietzsche  became  a  philosopher 
of  far-reaching  influence  only  after  he  had  passed  the  stage  of 
the  philologist.  As  far  as  our  present  discussion  is  concerned, 
the  question  is  narrowed  down  considerably  :  it  reduces  itself 
to  inquiring  whether  we  do  sufficient,  too  little,  or  too  much 
Greek  and  Latin.  I  must  remark  at  the  very  outset  that, 
formerly,  school  requirements  went  much  further  in  this 
respect  than  nowadays,  when  we  scarcely  meet  with  a  scholar 
even  in  the  upper  classes  who  knows  Latin  and  Greek  perfectly." 

It  is  just  this  fact  that  Einstein  regards  as  a  sign  of  im- 
provement and  a  result  of  examining  the  true  aims  of  a  school. 
He  continued  :  "  Man  must  be  educated  to  '  react  delicately  ' ; 


64  EINSTEIN  THE  SEARCHER 

he  is  to  acquire  and  develop  *  intellectual  muscles '  !  And 
the  methods  of  language  drill  are  much  less  suited  to  this  pur- 
pose than  those  of  a  more  general  training  that  gives  greatest 
weight  to  a  sharpening  of  one's  own  powers  of  reflection. 
Naturally,  the  inclination  of  the  pupil  for  a  particular  profession 
must  not  be  neglected,  especially  in  view  of  the  circumstance 
that  such  inclination  usually  asserts  itself  at  an  early  age, 
being  occasioned  by  personal  gifts,  by  examples  of  other 
members  of  the  family,  and  by  various  circumstances  that  affect 
the  choice  of  his  future  Hfe-work.  That  is  why  I  support  the 
introduction  into  schools,  particularly  schools  devoted  to 
classics,  of  a  division  into  two  branches  at,  say,  the  fourth 
form,  so  that  at  this  stage  the  young  pupil  has  to  decide  in 
favour  of  one  or  other  of  the  courses.  The  elementary  founda- 
tion to  the  fourth  form  may  be  made  uniform  for  all,  as  they  are 
concerned  with  factors  on  education  that  are  scarcely  open  to 
the  danger  of  being  exaggerated  in  any  one  direction.  If 
the  pupil  finds  that  he  has  a  special  interest  in  what  are 
called  humaniora  by  the  educationist,  let  him  by  all  means 
continue  along  the  road  of  Latin  and  Greek,  and,  indeed,  with- 
out being  burdened  by  tasks  that,  owing  to  his  disposition, 
oppress  or  alarm  him." 

"  You  are  referring,"  I  interposed,  "  to  the  distress  which 
pupils  feel  in  the  time  allotted  to  mathematics.  There 
are  actually  people  of  considerable  intelHgence  who  seem  to  be 
smitten  with  absolute  stupidity  when  confronted  with  mathe- 
matics, and  whose  school-hfe  becomes  poisoned  owing  to  the 
torment  caused  by  this  subject.  There  are  many  cases  of 
living  surgeons,  lawyers,  historians,  and  Utterateurs,  who,  till 
late  in  life,  are  visited  by  dreams  of  their  earlier  mathematical 
ordeals.  Their  horror  has  a  very  real  foundation,  for,  whereas 
the  pupil  who  is  bad  at  Latin  yet  manages  to  get  an  idea  of 
the  language,  and  he  who  is  weak  in  history  has  at  least  a  notion 
of  what  is  being  discussed,  the  one  who  is  unmathematical  by 
nature  has  to  worry  his  way  through  numberless  lessons  in 
a  subject  which  is  entirely  incomprehensible  to  him,  as  if 
belonging  to  another  world  and  being  presented  to  him  in  a 
totally  strange  tongue.  He  is  expected  to  answer  questions, 
the  sense  of  which  he  cannot  even  guess,  and  to  solve  problems, 
every  word  and  every  figure  of  which  glares  at  him  hke  a 


EDUCATION  65 

sphinx  of  evil  omen.  Sitting  on  each  side  of  him  are  pupils 
to  whom  this  is  merely  play,  and  some  of  whom  could  complete 
the  whole  of  school  mathematics  within  a  few  months  at  express 
rate.  This  leads  to  a  contrast  between  the  pupils,  which  may 
press  with  tragical  force  on  the  unfortunate  member  throughout 
his  whole  school  existence.  That  is  why  a  reform  is  to  be 
welcomed  that  sifts  out  in  time  those  who  should  be  separated 
from  the  rest,  and  which  adapts  the  school  curriculum  as  closely 
as  possible  to  individual  talents.'* 

Einstein  called  my  attention  to  the  fact  that  this  division 
had  already  been  made  in  many  schools  in  foreign  countries,  as 
in  France  and  in  Denmark,  although  not  so  exclusively  as 
suggested  by  him.  "  Moreover,*'  he  added,  "  I  am  by  no 
means  decided  whether  the  torments  that  you  mentioned  are 
founded  primarily  on  absence  of  talent  in  the  pupil.  I  feel 
much  more  incUned  to  throw  the  responsibihty  in  most  cases 
on  the  absence  of  talent  in  the  teacher.  Most  teachers  waste 
their  time  by  asking  questions  which  are  intended  to  discover 
what  a  pupil  does  not  know,  whereas  the  true  art  of  question- 
ing has  for  its  purpose  to  discover  what  the  pupil  knows  or 
is  capable  of  knowing.  Whenever  sins  of  this  sort  are  com- 
mitted— and  they  occur  in  all  branches  of  knowledge — the 
personahty  of  the  teacher  is  mostly  at  fault.  The  results  of 
the  class  furnish  an  index  for  the  quahty  of  the  preceptor. 
All  things  being  taken  into  consideration,  the  average  of 
abiUty  in  the  class  moves,  with  only  sHght  fluctuations, 
about  mean  values,  with  which  tolerably  satisfactory  results 
may  be  obtained.  If  the  progress  of  the  class  is  not  up  to 
this  standard,  we  must  not  speak  of  a  bad  year  but  rather 
of  an  inefficient  instructor.  It  may  be  assumed  that,  as  a 
rule,  the  teacher  understands  the  subject  with  which  he  is 
entrusted,  and  has  mastered  its  content,  but  not  that  he 
knows  how  to  impart  his  information  in  an  interesting  manner. 
This  is  almost  always  the  source  of  the  trouble.  If  the  teacher 
generates  an  atmosphere  of  boredom,  the  progress  is  stunted 
in  the  suffocating  surroundings.  To  know  how  to  teach  is  to 
be  able  to  make  the  subject  of  instruction  interesting,  to 
present  it,  even  if  it  happens  to  be  abstract,  so  that  the  soul 
of  the  pupil  resonates  in  sympathy  with  that  of  his  instructor, 
and  so  that  the  curiosity  of  the  pupil  is  never  allowed  to  wane." 
5 


66  EINSTEIN  THE  SEARCHER 

"  That  is  in  itself  an  ideal  postulate.  If  we  assume  it  to 
be  fulfilled,  how  do  you  wish  to  see  the  subjects  distributed  in 
the  curriculum  ?  '* 

"  We  must  leave  the  detailed  discussion  of  this  question 
for  another  occasion.  One  of  the  main  points  would  be  the 
economy  of  time  ;  all  that  is  superfluous,  vexatious,  and  only 
intended  as  a  drill  must  be  dropped.  At  present  the  aim  of 
the  whole  course  is  the  leaving  certificate.  This  test  must  be 
given  up  !  " 

"  Is  that  serious,  Professor  ?  Do  you  wish  to  do  away 
with  the  examination  for  matriculation  ?  '* 

"  Exactly.  For  it  is  hke  some  fearful  monster  guarding 
our  exit  from  school,  throwing  its  shadow  far  ahead,  and 
compelUng  teacher  and  pupil  to  work  incessantly  towards 
an  artificial  show  of  knowledge.  This  examination  has  been 
elevated  by  forcible  means  to  a  level  which  the  violently 
drilled  candidates  can  keep  only  for  a  few  hours,  and  is  then 
lost  to  sight  for  ever.  If  it  is  eliminated,  it  will  carry  away 
with  it  this  painful  drilling  of  the  memory ;  it  will  no  longer 
be  necessary  to  hammer  in  for  years  what  will  be  entirely  for- 
gotten within  a  few  months,  and  what  deserves  to  be  for- 
gotten. Let  us  return  to  Nature,  which  upholds  the  principle 
of  getting  the  maximum  amount  of  effect  from  the  minimum 
of  effort,  whereas  the  matriculation  test  does  exactly  the 
opposite.'* 

"  Yes,  but  who  is  then  to  be  allowed  to  enter  the  uni- 
versity ?  " 

"  Every  one  who  has  shown  himself  to  be  capable  not  only 
in  a  crucial  test  of  an  accidental  kind,  but  in  his  whole  be- 
haviour. The  teacher  will  be  the  judge  of  this,  and  if  he  does 
not  know  who  is  quaUfied,  he  again  is  to  be  blamed.  He  will 
find  it  so  much  the  easier  to  decide  who  is  sufficiently  advanced 
to  obtain  a  leaving  certificate,  in  proportion  as  the  curriculum 
has  weighed  less  on  the  minds  of  the  young  people.  Six  hours 
a  day  should  be  ample — ^f our  at  school  and  two  for  home-work  ; 
that  should  be  the  maximum.  If  this  should  appear  too  Uttle 
to  you,  I  must  ask  you  to  bear  in  mind  that  a  young  mind  is 
being  subjected  to  strain  even  in  leisure  hours,  as  it  has  to 
receive  a  whole  world  of  perceptions.  And  if  you  ask  how  the 
steadily  increasing  curriculum  is  to  be  covered  in  this  very 


EDUCATION  67 

moderate  number  of  hours,  my  answer  is :  Throw  all  that  is 
unnecessary  overboard  !  I  count  as  unnecessary  the  major 
part  of  the  subject  that  is  called  '  Universal  History/  and 
which  is,  as  a  rule,  nothing  more  than  a  blurred  mass  of  history 
compressed  into  dry  tables  of  names  and  dates.  This  subject 
should  be  brought  within  the  narrowest  possible  hmits,  and 
should  be  presented  only  in  broad  outUne,  without  dates  having 
to  be  crammed.  Leave  as  many  gaps  as  you  Mke,  especially 
in  ancient  history  ;  they  will  not  make  themselves  felt  in  our 
ordinary  existences.  In  nowise  can  I  regard  it  as  a  mis- 
fortune if  the  pupil  learns  nothing  of  Alexander  the  Great,  and 
of  the  dozens  of  other  conquerors  whose  documentary  remains 
burden  his  memory  hke  so  much  useless  baUast.  If  he  is  to 
get  a  gUmpse  of  the  grey  dawn  of  time,  let  him  be  spared  from 
Cyrus,  Artaxerxes,  and  Vercingetorix,  but  rather  tell  him 
something  of  the  pioneers  of  civiHzation,  Archimedes,  Ptolemy, 
Hero,  Appolonius,  and  of  inventors  and  discoverers,  so  that 
the  course  does  not  resolve  into  a  series  ot  adventures  and 
massacres." 

"  Would  it  not  be  expedient,"  I  interrupted,  "  to  take 
some  of  the  history  time  to  branch  off  into  an  elementary 
treatment  of  the  real  evolution  of  the  state,  including  sociology 
and  the  legal  code  ?  " 

Einstein  does  not  consider  this  desirable,  although  he  him- 
self is  deeply  interested  in  all  manifestations  of  pubUc  Ufe. 
He  does  not  favour  an  elementary  pohtical  training  received 
at  school,  presumably  above  all  owing  to  the  fact  that  in  this 
branch  the  instruction  cannot  be  removed  from  official  in- 
fluences, and  because  pohtical  questions  require  the  attention 
of  a  mature  mind.  His  picture  of  how  a  youth  is  to  meet  the 
requirements  of  modem  hfe  is  something  quite  different,  far 
removed  from  all  theories.  His  whole  efforts  are  directed  at 
finding  a  means  of  counteracting  the  tendency  to  overburden 
one  side  of  the  youthful  mind.  "  I  should  demand  the  intro- 
duction of  compulsory  practical  work.  Every  pupil  must 
learn  some  handicraft.  He  should  be  able  to  choose  for  him- 
self which  it  is  to  be,  but  I  should  allow  no  one  to  grow  up 
without  having  gained  some  technique,  either  as  a  joiner, 
bookbinder,  locksmith,  or  member  of  any  other  trade,  and 
without  having  dehvered  some  useful  product  of  his  trade." 


68  EINSTEIN  THE  SEARCHER 

"  Do  you  attach  greater  importance  to  the  technique  itself 
or  to  the  feehng  of  social  relationship  with  the  broad  masses  of 
the  people  which  it  engenders  ?  " 

"  Both  factors  are  equally  important  to  me,"  said  Einstein, 
"  and  others  become  added  to  these  which  help  to  justify  my 
wish  in  this  respect.  The  handiwork  need  not  be  used  as  a 
means  of  earning  money  by  the  pupil  of  the  secondary  school, 
but  it  will  enlarge  and  make  more  solid  the  foundation  on 
which  he  will  rest  as  an  ethical  being.  In  the  first  place,  the 
school  is  not  to  produce  future  officials,  scholars,  lecturers, 
barristers,  and  authors,  but  human  beings,  not  merely  mental 
machines.  Prometheus  did  not  begin  his  education  of  man- 
kind with  astronomy,  but  by  teaching  the  properties  of  fire 
and  its  practical  uses.  .  .  .'* 

*'  This  brings  to  my  mind  another  analogy,"  I  continued, 
"  namely,  that  of  the  old  Meister singer,  who  were,  all  of  them, 
expert  smiths,  tinkers,  or  shoemakers,  and  yet  succeeded  in 
building  a  bridge  to  the  arts.  And  at  bottom,  the  sciences, 
too,  belong  to  the  category  of  free  arts.  Yet,  a  difficulty  seems 
to  me  to  arise.  In  demanding  a  compulsory  handicraft,  you 
lay  stress  on  practical  use,  whereas  in  your  other  remarks  you 
declared  science  in  itself  as  being  utterly  independent  of 
practice." 

"  I  do  this,"  replied  Einstein,  "  only  when  I  speak  of  the 
ultimate  aims  of  pure  research,  that  is,  of  aims  that  are  visible 
to  only  a  vanishing  minority.  It  would  be  a  complete  mis- 
conception of  Hfe  to  uphold  this  point  of  view  and  to  expect 
its  regulative  effectiveness  in  cases  in  which  we  are  deahng 
only  with  the  preliminaries  of  science.  On  the  contrary,  I 
maintain  that  science  can  be  taught  much  more  practically 
at  schools  than  it  is  at  present  when  bookwork  has  the  upper 
hand.  For  example,  to  return  to  the  question  of  mathematical 
teaching  :  it  seems  to  me  to  be  almost  universally  at  fault,  if 
only  for  the  reason  that  it  is  not  built  up  on  what  is  practically 
interesting,  what  appeals  directly  to  the  senses,  and  what  can 
be  seized  intuitively.  Child-minds  are  fed  with  definitions 
instead  of  being  presented  with  what  they  can  grasp,  and  they 
are  expected  to  be  able  to  understand  purely  conceptual  things, 
although  they  have  had  no  opportunity  given  them  of  arriving 
at  the  abstract  by  way  of  concrete  things.     It  is  very  easy  to 


EDUCATION  69 

do  the  latter.  The  first  beginnings  should  not  be  taught  in  the 
schoolroom  at  all,  but  in  open  Nature.  A  boy  should  be  shown 
how  a  meadow  is  measured  and  compared  with  another.  His 
attention  must  be  directed  to  the  height  of  a  tower,  to  the 
length  of  his  shadow  at  various  times,  to  the  corresponding 
altitude  of  the  sim ;  by  this  means  he  will  grasp  the  mathe- 
matical relationships  much  more  rapidly,  more  surely,  and 
with  greater  zeal,  than  if  words  and  chalk-marks  are  used  to 
instil  into  him  the  conceptions  of  dimensions,  of  angles,  or 
perchance  of  some  trigonometrical  function.  What  is  the 
actual  origin  of  such  branches  of  science  ?  They  are  derived 
from  practice,  as,  for  example,  when  Thales  first  measured  the 
height  of  the  pyramids  with  the  help  of  a  short  rod,  which  he 
set  up  at  the  ultimate  point  of  the  pyramid's  shadow.  Place 
a  stick  in  the  boy's  hand  and  lead  him  on  to  make  experiments 
with  it  by  way  of  a  game,  and  if  he  is  not  quite  devoid  of  sense, 
he  will  discover  the  thing  for  himself.  It  wiU  please  him  to  have 
discovered  the  height  of  the  tower  without  having  cHmbed  it, 
and  this  is  the  first  thrill  of  the  pleasure  which  he  feels  later 
when  he  learns  the  geometry  of  similar  triangles  and  the 
proportionahty  of  their  sides." 

**  In  the  matter  of  physics,"  pursued  Einstein,  "  the  first 
lessons  should  contain  nothing  but  what  is  experimental  and 
interesting  to  see.  A  pretty  experiment  is  in  itself  often  more 
valuable  than  twenty  formulae  extracted  from  our  minds  ;  it  is 
particularly  important  that  a  young  mind  that  has  yet  to  find 
its  way  about  in  the  world  of  phenomena  should  be  spared  from 
formulae  altogether.  In  his  physics  they  play  exactly  the 
same  weird  and  fearful  part  as  the  figures  of  dates  in  Universal 
History.  If  the  experimenter  is  ingenious  and  expert,  this 
subject  may  be  begun  as  early  as  in  the  middle  forms,  and  one 
may  then  count  on  a  responsiveness  that  is  rarely  observable 
during  the  hours  of  exercise  in  Latin  grammar." 

"  This  leads  me,"  said  Einstein,  "  to  speak  in  this  con- 
nexion of  a  means  of  education  that  has  so  far  been  used  only 
by  way  of  trial  in  class-teaching,  but  from  an  improved  appUca- 
tion  of  which  I  expect  fruitful  results  later.  I  mean  the 
school  cinema.  The  triumphal  march  of  the  cinematograph 
will  be  continued  into  pedagogic  regions,  and  here  it  will  have 
a  chance  to  make  good  its  wrongs  in  thousands  of  picture  shows 


70  EINSTEIN  THE  SEARCHER 

in  showing  absurd,  immoral,  and  melodramatic  subjects.  By 
means  of  the  school-film,  supplemented  by  a  simple  apparatus 
for  projection,  it  would  be  possible  firstly  to  infuse  into  certain 
subjects,  such  as  geography,  which  is  at  present  wound  off 
organ-like  in  the  form  of  dead  descriptions,  the  pulsating  life 
of  a  metropolis.  And  the  lines  on  a  map  will  gain  an  entirely 
new  complexion  in  the  eyes  of  the  pupil,  if  he  learns,  as  if  during 
a  voyage,  what  they  actually  include,  and  what  is  to  be  read 
between  them.  An  abundance  of  information  is  imparted  by 
the  film,  too,  if  it  gives  an  accelerated  or  retarded  view  of  such 
things  as  a  plant  growing,  an  animal's  heart  beating,  or  the 
wing  of  an  insect  moving.  The  cinema  seems  to  me  to  have  a 
still  more  important  function  in  giving  pupils  an  insight  into 
the  most  important  branches  of  technical  industry,  a  know- 
ledge of  which  should  become  common  property.  Very  few 
hours  would  suffice  to  impress  permanently  on  the  schoolboy's 
mind  how  a  power-station,  a  locomotive,  a  newspaper,  a  book, 
or  a  coloured  illustration  is  produced,  or  what  takes  place  in 
an  electrical  plant,  a  glass  factory,  or  a  gasworks.  And,  to 
return  to  natural  science,  many  of  the  rather  difficult  experi- 
ments that  cannot  be  shown  by  means  of  school  apparatus 
may  be  shown  with  almost  as  great  clearness  on  a  film.  Taken 
all  in  all,  the  redeeming  word  in  school-teaching  is,  for  me : 
an  increased  appeal  to  the  senses.  Wherever  it  is  possible, 
learning  must  become  Hving,  and  this  principle  will  predominate 
in  future  reforms  of  school-teaching." 

University  study  was  only  touched  on  lightly  during  this 
talk.  It  has  become  known  that  Einstein  is  a  very  strong 
supporter  of  the  principle  of  free  learning,  and  that  he  would 
prefer  to  dispense  entirely  with  the  regular  documents  of  ad- 
mission which  qualify  holders  to  attend  lecture  courses.  This 
is  to  be  interpreted  as  meaning  that  as  soon  as  anyone  desirous 
of  furthering  his  studies  has  demonstrated  his  fitness  to  follow 
the  lecturer's  reasoning  by  showing  his  ability  in  class  exercises 
or  in  the  laboratory,  he  should  be  admitted  immediately. 
Einstein  would  not  demand  the  usual  certificate  of  "  general 
education,"  but  only  of  fitness  for  the  special  subject,  par- 
ticularly as,  in  his  own  experience,  he  has  frequently  found 
the  cleverest  people  and  those  with  the  most  definite  aims  to 


EDUCATION  71 

be  prone  to  one-sidedness.  According  to  this,  even  the  inter- 
mediate schools  should  be  authorized  to  bestow  a  certificate 
of  fitness  to  enter  on  a  course  in  a  single  definite  subject  as 
soon  as  the  pupil  has  proved  himself  to  have  the  necessary 
abihty.  If  he  earher  spoke  in  favour  of  aboHshing  the  matricu- 
lation examination,  this  is  only  an  indication  of  his  effort  to 
burst  open  the  portals  of  higher  education  for  every  one. 
Nevertheless,  I  remarked  that,  in  the  course  of  university  work 
itself,  he  is  not  in  favour  of  giving  up  all  regulation  concerning 
the  ability  of  the  student — at  least,  not  in  the  case  of  those  who 
intend  to  devote  themselves  to  instruction  later.  He  does  not 
desire  an  intermediate  examination  (in  the  nature  of  the 
tentamen  physicum  of  doctors),  but  he  considers  it  profitable 
for  the  future  schoolmaster  to  have  an  opportunity  early  in 
his  course  to  prove  his  fitness  for  teaching.  In  this  matter, 
too,  Einstein  reveals  his  affectionate  interest  in  the  younger 
generation,  whose  development  is  threatened  by  nothing  so 
much  as  by  incapable  teachers  :  the  sum  of  these  considera- 
tions is  that  the  pupil  is  examined  as  httle  as  possible,  but 
the  teacher  so  much  the  more  closely.  A  candidate  for  the 
teaching  profession,  who  in  the  early  stages  of  his  academic 
career  fails  to  show  his  fitness,  his  individual  facuUas  docendi, 
should  be  removed  from  the  university. 

There  can  be  no  doubt  but  that  Einstein  has  a  claim  to 
be  heard  as  an  authority  on  these  questions.  There  are  few 
in  the  realm  of  the  learned  in  whose  faces  it  is  so  clearly 
manifest  that  they  are  called  to  excite  a  desire  for  knowledge 
by  means  of  the  hving  word,  and  to  satisfy  this  desire.  If 
great  audiences  assemble  around  him,  if  so  many  foreign 
academies  open  their  arms  to  him  to  make  him  their  own, 
these  are  not  only  signs  of  a  magnetic  influence  that  emanates 
from  the  famous  discoverer,  but  they  are  indications  that  he 
is  far  famed  as  a  teacher  with  a  captivating  personality. 
Let  us  consider  what  this  signifies  in  his  profession.  Philo- 
sophers, historians,  lawyers,  doctors,  and  theologians  have  at 
their  disposal  innumerable  words  which  they  merely  need  to 
pronounce  to  get  into  immediate  contact  with  their  audiences. 
In  Einstein's  profession,  theoretical  physics,  man  disappears  ; 
it  leaves  no  scope  for  the  play  of  emotion  ;  its  implement 
mathematics — and  what  an  instrument  it  is  ! — bristles  with 


72  EINSTEIN  THE  SEARCHER 

formal  difl&culties,  which  can  be  overcome  only  by  means  of 
symbols  and  by  using  a  language  which  has  no  means  of 
(Msplaying  eloquence,  being  devoid  of  expression,  emotion, 
and  regular  periods.  Yet  here  we  have  a  physicist,  a  mathe- 
matician, whose  first  word  throws  a  charm  over  a  great  crowd 
of  people,  and  who  extracts  from  their  minds,  so  to  speak, 
what,  in  reality,  he  alone  works  out  before  them.  He  does 
not  adhere  closely  to  written  pages,  nor  to  a  scheme  which 
has  been  prepared  beforehand  in  all  its  details  ;  he  develops 
his  subject  freely,  without  the  shghtest  attempt  at  rhetoric, 
but  with  an  effect  which  comes  of  itself  when  the  audience 
feels  itself  swept  along  by  the  current.  He  does  not  need 
to  deliver  his  words  passionately,  as  his  passion  for  teaching 
is  so  manifest.  Even  in  regions  of  thought  in  which  usually 
only  formulae,  hke  glaciers,  give  an  indication  of  the  height, 
he  discovers  similes  and  illustrations  with  a  human  appeal, 
by  the  aid  of  which  he  helps  many  a  one  to  conquer  the 
mountain  sickness  of  mathematics.  His  lectures  betray  two 
factors  that  are  rarely  found  present  in  investigators  of  abstract 
subjects ;  they  are  temperament  and  geniaUty.  He  never 
talks  as  if  in  a  monologue  or  as  if  addressing  empty  space. 
He  always  speaks  Hke  one  who  is  weaving  threads  of  some 
idea,  and  these  become  spun  out  in  a  fascinating  way  that 
robs  the  audience  of  the  sense  of  time.  We  all  know  that  no 
iron  curtain  marks  the  close  of  Einstein's  lecture ;  anyone 
who  is  tormented  by  some  difficulty  or  doubt,  or  who  desires 
illumination  on  some  point,  or  has  missed  some  part  of  the 
argument,  is  at  Hberty  to  question  him.  Moreover,  Einstein 
stands  firm  through  the  storm  of  all  questions.  On  the  very 
day  on  which  the  above  conversation  took  place  he  had  come 
straight  from  a  lecture  on  four-dimensional  space,  at  the  con- 
clusion of  which  a  tempest  of  questions  had  raged  about  him. 
He  spoke  of  it  not  as  of  an  ordeal  that  he  had  survived,  but 
as  of  a  refreshing  shower.  And  such  delights  abound  in  his 
teaching  career. 

It  was  the  last  lecture  before  his  departure  for  Leyden 
(in  May  1920),  where  the  famous  faculty  of  science,  under  the 
auspices  of  the  great  physicist  Lorentz,  had  invited  him  to 
accept  an  honorary  professorship.     This  was  not  the  first 


EDUCATION  73 

invitation  of  this  kind,  and  \\ill  not  be  the  last,  for  distinctions 
are  being  showered  on  him  from  all  parts  of  the  world.  It 
is  true  that  the  universities  who  confer  a  degree  on  him 
honoris  causa  are  conferring  a  distinction  on  themselves,  but 
Einstein  frankly  acknowledges  the  value  of  these  honours, 
which  he  regards  as  referring  only  to  the  question  in  hand, 
and  not  the  person.  It  gives  him  pleasure  on  account  of  the 
principle  involved  being  recognized,  and  he  regards  himself 
essentially  only  as  one  whom  fate  has  ordained  as  the  personal 
exponent  of  these  principles. 

What  this  hf  e  of  hustle  and  bustle  about  a  scientist  signifies 
is  perhaps  more  apparent  to  me,  who  have  a  modest  share 
in  these  conversations,  than  to  Einstein  himself,  for  I  am  an 
old  man  who — imfortunately — have  to  think  back  a  long  way 
to  my  student  days,  and  can  set  up  comparisons  which  are 
out  of  reach  of  Einstein.  Formerly,  many  years  ago,  but  in 
my  own  time,  there  was  an  auditorium  maximum  which  only 
one  man  could  manage  to  fill  with  an  audience,  namely,  Eugen 
Diihring,  the  noted  scholar,  who  was  doomed  to  remain  a 
lecturer  inasmuch  as  he  went  under  in  his  quarrels  with 
confreres  of  a  higher  rank.  But  before  he  made  his  onslaught 
against  Helmholtz,  he  was  regarded  as  a  man  of  unrivalled 
magnetic  power,  for  his  philosophical  and  economical  lectures 
gathered  together  over  three  hundred  hearers,  a  record 
number  in  those  times.  Nowadays,  in  the  case  of  Einstein, 
four  times  this  number  has  been  siupassed,  a  fact  which  has 
brought  into  circulation  the  playful  saying :  One  can  never 
miss  his  auditorium ;  whither  all  are  hastening,  that  is  the 
goal !  To  make  just  comparisons,  we  must  take  account  of 
the  faithfulness  of  the  assembled  crowd,  as  well  as  its  number. 
Many  an  eminent  scholar  has  in  earher  times  had  reason  to 
declare,  hke  Faust :  **  I  had  the  power  to  attract  you,  yet  had 
no  power  to  hold  you."  Helmholtz  began  regularly  every 
term  with  a  crowded  lecture-hall,  but  in  a  short  time  he  foimd 
himself  deserted,  and  he  himself twas'^  weU^  aware  that  no 
magnetic  teaching  influence  emanated  from  him.  There  is 
yet  another  case  in  university  history  of  a  brilliant  personaUty 
who,  from  similar  flights  of  ecstasy,  was  doomed  to  disappoint- 
ment. I  must  mention  his  name,  which,  in  this  connexion, 
will  probably  cause  great  surprise,  namely,  Schiller  !     He  had 


74  EINSTEIN  THE  SEARCHER 

fixed  his  first  lecture  in  history  at  Jena,  to  which  he  was 
appointed,  and  had  prepared  for  an  audience  of  about  a 
hundred  students.  But  crowd  upon  crowd  hustled  along,  and 
Schiller,  who  saw  the  oncoming  stream  from  his  window,  was 
overcome  with  the  impression  that  there  was  no  end  to  it. 
The  whole  street  took  alarm,  for  at  first  it  was  imagined  that 
a  fire  had  broken  out,  and  at  the  palace  the  watch  was  called 
out — yet,  a  little  later  in  the  course,  there  was  a  depressing 
ebb  of  the  tide,  after  the  first  curiosity  had  been  appeased ; 
the  audience  gradually  vanished  into  thin  air,  a  proof  of  the 
fact  that  the  nimbus  of  a  name  does  not  suffice  to  maintain 
the  interest  between  the  lecturer's  desk  and  the  audience. 

I  mentioned  this  example  at  the  time  when  Einstein's  gift 
for  teaching  had  gradually  increased  the  number  of  his  hearers 
to  the  record  figure  of  1200,  yet  I  did  not  on  this  occasion 
detect  any  inordinate  joy  in  him  about  his  success.  I  gained 
the  impression  that  he  had  strained  his  voice  in  the  vast  hall. 
His  mood  betrayed  in  consequence  a  slight  undercurrent  of 
irritation.  In  an  access  of  scepticism  he  murmured  the  words, 
"  A  mere  matter  of  fashion."  I  cannot  imagine  that  he  was 
entirely  in  earnest.  It  goes  without  saying  that  I  protested 
against  the  expression.  But,  even  if  there  were  a  particle  of 
truth  in  it,  we  might  well  be  pleased  to  find  such  a  fashion 
in  intellectual  matters,  one  that  persists  so  long  and  promises 
to  last.  The  world  would  recover  its  normal  healthy  state 
if  fashions  of  this  kind  were  to  come  into  full  swing.  It  is, 
of  course,  easy  to  understand  on  psychological  grounds  that 
Einstein  himself  takes  up  a  sort  of  defensive  position  against 
his  own  renown,  and  that  he  occasionally  tries  to  attack  it 
by  means  of  sarcasm,  seeing  that  he  cannot  find  serious  argu- 
ments to  oppose  it. 

Whether  Einstein's  ideas  and  proposals  concerning  educa- 
tional reform  will  be  capable  of  reaUzation  throughout  is  a 
question  that  time  alone  can  answer.  We  must  make  it  clear 
to  ourselves  that,  if  carried  out  along  free-thinking  lines,  they 
will  demand  certain  sacrifices,  and  it  depends  on  the  apportion- 
ment of  these  sacrifices  as  to  what  the  next,  or  the  following, 
generation  will  have  to  exhibit  in  the  way  of  mental  training. 

An  appreciable  restriction  will  have  to  be  imposed  on  the 


EDUCATION  75 

time  given  to  languages.  It  is  a  matter  of  deciding  how  far 
this  will  affect  the  foundations  that,  under  the  collective  term 
humaniora,  have  supported  the  whole  system  of  classical  schools 
for  centuries.  The  fundamental  ideas  of  reform,  which,  owing 
to  the  redivision  of  school-hours  and  the  economy  of  work,  no 
longer  claim  precedence  for  languages,  indicate  that  not  much 
will  be  left  of  the  original  Latin  and  Greek  basis. 

We  have  noticed  above  that  Einstein,  although  he  does  not, 
in  principle,  oppose  the  old  classicism,  no  longer  expects  much 
good  of  it.  But  nowadays  the  state  of  affairs  is  such  that  it  is 
hardly  a  question  of  supporting  or  opposing  its  retention  in 
fragmentary  form.  Whoever  does  not  support  it  with  all  his 
power  strengthens  indirectly  the  mighty  chorus  of  those  who 
are  radically  antagonistic  to  it.  And  it  is  a  remarkable  fact 
that  this  chorus  includes  many  would-be  authorities  on 
languages  who  have  influence  among  us  because  they  are 
champions  of  the  cause  of  retaining  languages. 

They  do  not  wish  to  rescue  languages  as  such,  but  only  the 
German  tongue ;  they  point  to  the  humaniora  of  classical 
schools,  or  to  Humanisterei,  as  they  call  it,  as  the  enemy  and 
corrupter  of  their  language.  In  what  sense  they  mean  this  is 
obvious  from  their  articles  of  faith,  of  which  I  should  like  to 
cite  a  few  in  the  original  words  of  one  of  their  party-leaders  : 

"  Up  to  the  time  of  the  hazardous  enterprise  of  Thomasius 
(who  first  announced  lectures  in  the  German  language  in  1687) 
German  scholars  as  a  body  were  the  worst  enemies  of  their 
own  tongue. — Luther  did  not  take  his  models  for  writing 
German  from  the  humanistic  mimics  who  aped  the  old  Latins. 
In  the  case  of  many,  including  Lessing  and  Goethe,  we  observe 
them  making  a  definite  attempt  to  shake  themselves  free  from 
the  chaos  of  humanistic  influences  in  Germany. — The  inherit- 
ance of  pseudo-learned  concoctions  of  words  stretches  back 
to  pretentious  humanism  as  do  most  of  essential  vices  of  learned 
styles. — The  far-reaching  and  lasting  corruption  of  the  German 
language  by  this  poisonous  Latin  has  its  beginnings  in  the 
humanism  of  the  sixteenth  century.*' 

And,  quite  logically,  these  heralds  extend  their  attacks 
along  the  whole  academic  front.  For,  according  to  their  point 
of  view,  the  whole  army  of  professors  is  deeply  immersed  in 
the  language  shme  of  the  traditional  humanism  of  the  Greeks 


76  EINSTEIN  THE  SEARCHER 

and  Latins.  "  The  whole  language  evil  of  our  times/'  so  these 
leaders  say,  **is  at  bottom  due  to  scientists,  who,  in  the  opinion- 
ated guise  of  a  language  caste,  and  without  enriching  our 
conceptions  in  the  slightest,  seek  by  tinkhng  empty  words  to 
give  us  the  illusion  of  a  new  and  particularly  mysterious  occult 
science,  an  impression  which  is  unfortunately  often  produced 
on  ignorant  minds.  .  .  .  However  many  muddy  outlets 
official' institutions  and  language  associations  may  purge  and 
block  up,  ditch-water  from  ever  new  quagmires  and  drains 
pours  unceasingly  into  the  stately  stream  of  our  language." 

Thus  the  attack  on  the  Latin  and  Greek  language  founda- 
tion in  schools  identifies  itself  with  the  struggle  against  the 
academic  world  as  a  whole,  and  a  scholar  who  does  defend 
the  classical  system  of  education  with  all  his  might  finds  himself 
unconsciously  drifting  into  the  ranks  of  the  brotherhood  which 
in  the  last  instance  is  seeking  his  own  extermination. 

This  danger  must  not  be  under-estimated.  It  is  just  this 
peril,  so  threatening  to  our  civihzation,  that  moves  me  to  show 
my  colours  frankly  here.  I  am  not  a  supporter  of  bookworm 
drudgery  in  schools,  but  I  feel  myself  impelled  to  use  every 
effort  in  speech  and  writing  to  combat  the  anti-humanists 
whose  password,  "  For  our  language,"  at  root  signifies 
"  Enemies  of  Science  !  " 

We  must  put  no  weapons  into  their  hands,  and  the  only 
means  to  avoid  this  is,  in  my  opinion,  to  state  our  creed 
emphatically  and  openly  after  the  manner  of  almost  all  our 
classical  writers. 

This  creed,  both  as  regards  language  and  substance,  is  to 
be  understood  as  being  based  on  the  efiicacy  of  the  old  classical 
languages.  It  is  the  luminous  centre  of  the  life  and  work  of 
the  men  who  caused  Bulwer  to  proclaim  our  country  the  country 
of  poets  and  thinkers.  The  superabundance  of  these  is  so 
excessive  that  it  is  scarcely  fair  to  mention  only  a  few  names 
such  as  Goethe,  Lessing,  Schiller,  Wieland,  Kant,  and  Schopen- 
hauer. Our  Hterature  would  be  of  a  provincial  standard  and 
not  a  world  possession  if  this  creed  had  not  asserted  its 
sway  at  all  times. 

If  the  question  is  raised  as  to  where  our  youth  is  to  find 
time  for  learning  ancient  languages  under  the  present  condi- 
tions of  crowded  subjects,  the  answer  is  to  be  furnished  by 


EDUCATION  77 

improved  methods  of  instruction.  My  personal  point  of  view 
is  that  even  the  older  methods  were  not  so  bad.  Goethe  found 
himself  in  no  wise  embarrassed  through  lack  of  time  in  acquiring 
all  sorts  of  knowledge  and  mental  equipment,  although  even  as 
a  boy  of  eight  years  he  could  write  in  Latin  in  a  way  which, 
compared  with  the  bungling  efforts  of  the  modem  sixth-form 
boy,  seems  Ciceronian.  Montaigne  could  express  himself 
earUer  in  Latin  than  in  French,  and  if  he  had  not  had  this 
"  Latin  poison  '*  injected  into  his  blood  he  would  never  have 
become  Montaigne. 

It  seems  to  me  by  no  means  impossible  that  the  cultured 
world  will  one  day  in  the  distant  future  return  to  the  once 
self-evident  view  of  classical  languages,  and  indeed  just  for 
reasons  of  economy  of  time,  unless  the  universal  language  so 
ardently  desired  by  Hebbel — ^not  to  be  confused  with  the 
artificial  patchwork  called  Esperanto — should  become  a  reaUty. 
But  even  this  language,  at  present  Utopian,  but  one  which  will 
help  to  link  together  the  nations,  will  disclose  the  model  of  the 
ancient  languages  in  its  structure.  Scientific  language  of  the 
present  day  shows  where  the  route  lies  ;  and  this  route  will  be 
made  passable  in  spite  of  all  the  efforts  of  Teutonic  language 
saints  and  assassins  of  humanism  to  block  it. 

The  working  out  of  ideas  by  research  scientists  leads  to 
enrichment  of  language.  And  since,  as  is  quite  natural,  they 
draw  copiously  on  antique  forms  of  expression,  they  are  really 
the  trustees  of  an  instruction  that  makes  these  expressions 
intelligible  not  merely  as  components  of  an  artificial  language 
like  Volapiik  but  as  organic  growths.  That  is  how  they  pro- 
ceed when  they  carry  on  their  research,  or  describe  it  and 
lecture  on  their  own  subject.  But  if  they  are  to  decide  how 
the  school  is  to  map  out  its  course  in  actual  practice,  the  prob- 
lem of  time  again  becomes  their  chief  consideration — that  is, 
they  feel  in  duty  bound  to  give  preference  to  what  is  most 
important.  Hence  there  results  the  wish  to  reduce  the  hours 
apportioned  to  the  language  subjects  as  much  as  possible. 

On  this  matter  we  have  a  detailed  essay  by  the  distinguished 
Ernst  Mach  mentioned  earUer,  who  exposes  the  actual  dilemma 
with  the  greatest  clearness.  He  treats  this  exceedingly  im- 
portant question  in  all  its  phases,  and  arrives  at  almost  the 
same  conclusion  as  Einstein.     At  the  outset  he  certainly  chants 


78  EINSTEIN  THE  SEARCHER 

a  Latin  psalm  almost  in  the  manner  of  Schopenhauer.  Its 
lower  tones  represent  an  elegy  lamenting  that  Latin  is  no 
longer  the  universal  language  among  educated  people,  as  it 
was  from  the  fifteenth  to  the  eighteenth  century.  Its  fitness 
for  this  purpose  is  quite  indisputable,  for  it  can  be  adapted  to 
express  every  conception  however  modern  or  subtle  it  may  be. 

What  a  profusion  of  new  conceptions  was  introduced  into 
science  by  Sir  Isaac  Newton,  to  all  of  which  he  succeeded  in 
giving  correct  and  precise  Latin  names  !  The  natural  inference 
suggests  itself  to  us  that  young  people  should  learn  the  ancient 
classical  tongues — and  yet  a  different  result  is  coming  about ; 
the  modern  child  is  to  be  content  with  understanding  words 
with  a  world-wide  currency,  without  knowing  their  philological 
origin. 

It  is  not  necessary  to  be  a  schoolmaster  to  feel  the  in- 
adequacy of  this  proceeding.  It  is  true  that  without  knowing 
Arabic  we  can  grasp  the  sense  and  meaning  of  the  word 
**  Algebra,"  and  in  the  same  way  we  can  extract  the  essence  of 
a  number  of  Greek  and  Latin  expressions  without  digging  at 
their  etymological  roots.  But  these  expressions  are  to  be 
counted  in  hundreds  and  thousands,  and  are  increasing  daily, 
so  that  we  are  put  before  the  question  whether,  merely  from 
the  point  of  view  of  time,  it  is  practicable  to  learn  them  as 
individual  foreign  terms  or  as  natural  products  of  a  root 
language  with  which  we  have  once  and  for  all  become  familiar. 

It  is  scarcely  necessary  for  me  to  point  out  that  Einstein 
himself  is  not  sparing  in  the  use  of  these  technical  expressions, 
even  when  he  is  using  popular  language.  He  assumes  or 
introduces  terms  of  which  the  following  are  a  few  examples : 
continuum,  co-ordinate  system,  dimensional,  electrodynamics, 
kinetic  theory,  transformation,  covariant,  heuristic,  parabola, 
translation,  principle  of  equivalence,  and  he  is  quite  justified 
in  assuming  that  every  one  is  fully  acquainted  with  such 
generally  accepted  expressions  as :  gravitation,  spectral 
analysis,  balHstic,  phoronomy,  infinitesimal,  diagonal,  com- 
ponent, periphery,  hydrostatics,  centrifugal,  and  numberless 
others  which  are  diffused  through  educated  popular  language 
in  all  directions.  Taken  all  together  these  represent  a  foreign 
realm  in  which  the  entrant  can  always  succeed  in  orientating 
himself  when  he  receives  explanations,  examples,  or  transla- 


EDUCATION  79 

tions,  whereas  with  a  little  preliminary  knowledge  of  the 
ancient  languages  he  immediately  feels  himself  at  home  with 
them ;  in  this  we  have  not  even  taken  into  consideration  the 
general  cultural  value  of  this  training  in  view  of  the  access  it 
gives  to  the  old  Hterature  and  to  Hellenic  culture. 

Perhaps  I  am  going  too  far  in  adopting  the  attitude  of 
a  laudator  temporis  acti  towards  Einstein's  very  advanced 
opinion.  We  are  here  deahng  with  a  question  in  which  nothing 
can  be  proved,  and  in  which  everything  depends  on  disposition 
and  personal  experiences.  In  my  own  case  this  experience 
includes  the  fact  that  at  a  very  early  age,  in  spite  of  the  very 
discouraging  school  methods,  I  enjoyed  the  study  of  Latin  and 
Greek,  and  that  I  learned  Horatian  odes  by  heart,  not  because 
I  had  to,  but  because  they  appealed  to  me,  and  finally  that 
Homer  opened  up  a  new  world  to  me.  When  Einstein  ex- 
presses his  abhorrence  of  drill,  I  agree  with  him  ;  but  these 
languages  need  not  be  taught  as  if  we  are  on  parade.  We  see 
thus  that  it  is  a  question  of  method  and  not  of  the  subject 
involved.  Einstein  gives  the  subject  its  due  by  recommend- 
ing a  double  series  of  classes.  He  allows  the  paths  to  diverge, 
giving  his  special  blessing  to  the  group  along  the  one  without 
setting  up  obstacles  to  prevent  the  other  pilgrims  from  attain- 
ing happiness  in  their  own  way. 

We  spoke  of  higher  education  for  women,  and  Einstein 
expressed  his  views  which,  as  was  to  be  expected,  were  tolerant, 
and  yet  did  not  suggest  those  of  a  champion  of  the  cause.  It 
was  impossible  to  overlook  the  fact  that  in  spite  of  his  approval 
he  had  certain  reservations  of  a  theoretical  nature. 

"  As  in  all  other  directions,"  he  said,  "  so  in  that  of  science 
the  way  should  be  made  easy  for  women.  Yet  it  must  not  be 
taken  amiss  if  I  regard  the  possible  results  with  a  certain 
amoimt  of  scepticism.  I  am  referring  to  certain  obstacles  in 
woman's  organization  which  we  must  regard  as  given  by 
Nature,  and  which  forbid  us  from  applying  the  same 
standard  of  expectation  to  women  as  to  men." 

"  You  beheve,  then.  Professor,  that  high  achievements 
cannot  be  accomplished  by  women  ?  To  keep  our  attention 
on  science,  can  one  not  quote  Madame  Curie  as  a  proof  to  the 
contrary  ?  " 


80  EINSTEIN  THE  SEARCHER 

"  Surely  only  as  one  proof  of  brilliant  exceptions,  more 
of  which  may  occur  without  refuting  the  statute  of  sexual 
organization." 

"  Perhaps  this  will  be  possible  after  all  if  a  sufficient  time 
for  development  be  allowed.  There  may  be  much  fewer 
geniuses  among  the  other  sex,  but  there  has  certainly  been  a 
concentration  of  talent.  Or,  in  other  words,  totally  ignorant 
women  have  become  much  rarer.  You,  Professor,  are  for- 
tunate in  not  being  in  a  position  to  compare  young  women 
of  to-day  with  those  of  forty  or  more  years  ago.  This  I  can 
do,  and  just  as  once  I  found  it  natural  that  there  should  be 
swarms  of  little  geese  and  peacocks,  I  never  recover  from  my 
astonishment  nowadays  at  the  amount  of  knowledge  acquired 
by  young  womanhood.  It  requires  a  considerable  effort  on 
my  part  very  often  to  avoid  being  completely  overshadowed 
by  a  partner  at  dinner.  The  more  this  stratum  of  talent 
increases,  the  more  we  have  reason  to  expect  a  greater  number 
of  geniuses  from  them  in  the  future." 

"  You  are  given  to  prognostication,"  said  Einstein,  "  and 
calculate  with  probabiUties  which  sometimes  are  lacking  in 
foundation.  Increased  education  and  even  an  increase  of 
talents  are  quantitative  assumptions  that  make  an  inference 
regarding  higher  quaUty  reaching  to  genius  appear  very  bold." 
— A  passing  look  of  ominous  portent  flashed  over  his  face,  and 
I  noticed  that  he  was  preparing  to  launch  a  sarcastic  aphorism. 
So  it  was,  for  the  next  words  were  :  "  It  is  conceivable  that 
Nature  may  have  created  a  sex  without  brains  !  " 

I  grasped  the  sense  of  this  grotesque  remark,  which  was  in 
no  way  to  be  taken  literally.  It  was  intended  as  an  amusing 
exaggeration  of  what  he  had  earlier  called  the  reason  for  his 
failing  expectation :  the  organic  difference  which,  being 
rooted  in  the  physical  constitution,  had  somewhere  to  express 
itself  on  the  mental  plane,  too.  The  soul  of  woman  strong  in 
impulse  shows  a  refinement  of  feehng  of  which  we  men  are 
not  susceptible,  whereas  the  greatest  achievements  of  reason 
probably  depend  on  a  preponderance  of  brain  substance.  It  is 
this  plus  beyond  the  normal  amount  that  gives  promise  of 
great  discoveries,  inventions,  and  creations.  We  can  just 
as  little  imagine  a  female  Galilei,  Kepler,  and  Descartes,  as  a 
female  Michelangelo  or  Sebastian  Bach.    But  when  we  think 


EDUCATION  81 

of  these  extreme  cases,  let  us  also  recall  the  balance  on  the 
other  side  :  although  a  woman  could  not  create  the  differential 
calculus,  it  was  she  that  created  Leibniz ;  similarly  she  pro- 
duced Kant  if  not  the  Critique  of  Pure  Reason.  Woman,  as 
the  author  of  all  great  minds,  has  at  least  a  right  of  access  to 
all  means  of  education  and  to  all  advancement  that  is  proffered 
by  universities.  And  in  this  connexion  Einstein  expressed  his 
wish  clearly  enough. 

One  of  the  most  discussed  themes  in  matters  touching 
school  education  is  at  the  present  time :  *  *  the  selection  of 
gifted  pupils."  It  has  developed  into  a  principle  that  is 
generally  recognized  by  the  great  majority,  the  only  point 
of  disagreement  being  in  respect  to  the  number  that  is  to  be 
selected. 

The  idea  running  through  it  is  that  derived  from  Darwin's 
theory  of  selection  :  man  completes  the  method  of  selection 
practised  by  Nature.  He  sifts  and  chooses,  and  allows  those 
that  are  more  talented  to  come  to  the  fore  more  rapidly  and 
more  decidedly  ;  he  favours  their  advancement  and  makes  easy 
their  ascent. 

This  principle  has  really  always  been  in  existence.  It 
started  with  the  distribution  of  prizes  in  ancient  Olympia  and 
reaches  to  the  present-day  examinations  that  are  clearly  in- 
tended as  a  means  of  selecting  talents.  A  greater  discrimina- 
tion based  on  a  systematic  search  for  talents  was  reserved  for 
our  own  day. 

It  was  scarcely  a  matter  of  doubt  to  me  what  attitude 
Einstein  would  take  up  towards  this  matter.  I  had  already 
heard  him  say  hard  words  about  the  system  of  examinations, 
and  knew  his  leaning  towards  allowing  each  mind  to  develop 
its  power  freely  and  naturally. 

In  effect,  Einstein  declared  to  me  that  he  would  hear 
nothing  of  a  breeding  of  talents  in  a  sort  of  sporting  way. 
The  dangers  of  the  methods  of  sport  would  creep  in  and  lead  to 
results  that  had  only  the  appearance  of  truth.  From  the 
results  so  far  obtained  it  was  impossible  to  come  to  a  final 
decision  about  it.  Yet  it  was  conceivable  that  a  selective 
process  conducted  along  reasonable  lines  would  in  general 
prove  of  advantage  in  education,  particularly  in  the  respect 
6 


82  EINSTEIN  THE  SEARCHER 

that  many  a  talent  that  would  ordinarily  become  stunted 
owing  to  its  being  kept  in  darkness  would  now  have  an  oppor- 
tunity of  coming  to  light. 

This  resolved  itself  into  a  talk  bearing  on  many  questions, 
and  of  which  I  should  hke  to  state  the  main  issue  here.  It 
was  specially  intended  to  make  clear  the  gambUng  method 
that  Einstein  repudiates,  and  the  danger  of  which  seems  still 
more  threatening  to  me  than  to  him. 

If  certain  pedagogues,  whose  creed  is  force,  were  to  have 
their  way,  the  "  most  gifted  "  pupils  would  be  able,  or  would 
be  compelled,  to  rush  through  school  at  hurricane  speed,  and, 
at  an  age  at  which  their  fellows  were  still  spending  weary 
hours  at  their  desks,  they  would  have  to  clamber  to  the  top- 
most branches  of  the  academic  tree.  All  things  are  possible, 
and  history  even  furnishes  cases  of  such  forced  marches. 
Luther's  friend  Melanchthon  quaUfied  at  the  age  of  thirteen 
to  enter  the  University  of  Heidelberg,  and  at  the  age  of  seven- 
teen he  became  a  professor  at  Tiibingen,  where  he  gave  lectures 
on  the  most  difi&cult  problems  of  philosophy,  as  well  on  the 
Roman  and  Greek  writers  of  classical  antiquity.  This  single 
instance  need  only  be  generahzed,  and  we  have  the  new  ideal 
rising  up  before  our  astonished  gaze :  a  race  of  professorial 
striphngs  whose  upper  Hps  are  scarcely  darkened  with  the 
down  of  youth  I  It  is  a  mere  matter  of  making  an  early 
discovery  of  the  most  gifted,  and  then  raising  the  scaffolding 
up  which  the  precocious  know-aUs  can  climb  as  easily  as 
possible. 

[Interposed  query :  Where  are  these  discoverers  of  talent, 
and  how  do  they  prove  their  own  talent  ?  There  was  a  good 
opportunity  for  them  in  a  case  which  I  must  here  mention. 
Einstein  told  me  in  another  connexion  that,  as  early  as  1907, 
that  is,  when  he  was  stiU  very  young  in  years,  he  had  not 
only  succeeded  in  successfully  representing  the  Principle  of 
Equivalence,  one  of  the  main  supports  of  the  General  Principle 
of  Relativity,  but  had  even  published  it ;  yet  it  made  not  the 
shghtest  impression  on  the  learned  world.  No  one  suspected 
the  far-reaching  consequences,  and  no  one  pointed  out  this 
flaming  up  of  a  new  talent  of  the  highest  order.  And  just  as 
this  was  able  to  remain  concealed  from  the  learned  Areopagus 
of  the  world  at  that  time,  so  a  similar  lack  of  understanding 


EDUCATION  88 

may  easily  be  possible  on  a  smaller  scale  at  school.  We  know 
actually  that  among  the  recognized  great  men  of  science, 
there  were  many  who  did  only  moderately  well  at  school ; 
as,  for  example,  Humphry  Davy,  Robert  Mayer,  Justus 
Liebig,  and  many  others.  Wilhelm  Ostwald  goes  so  far  as  to 
affirm :  '*  Boys  ordained  to  be  discoverers  later  in  life  have, 
almost  without  exception,  been  bad  at  school  I  It  is  just  the 
most  gifted  young  people  who  have  resisted  most  strongly 
the  form  of  intellectual  development  prescribed  by  the  school ! 
Schools  never  cease  to  show  themselves  to  be  the  bitter, 
unrelenting  enemies  of  genius  I  " — ^in  spite  of  all  efiorts  at 
selection  which  have  always  been  in  vogue  in  the  guise  of 
advancement  into  higher  forms.] 

But  the  new  mode  of  selection  is  intended  to  prevent 
mistakes  and  oversights.  Is  this  possible  ?  Do  not  the  traces 
of  previous  attempts  inspire  distrust  ?  There  was  once  a 
very  ideal  selection  that  had  to  stand  the  test  of  one  of  the 
most  eminent  bodies  in  existence,  the  French  Academy.  Its 
duty  was  to  discover  geniuses  on  an  incomparably  higher 
plane.  It,  however,  repudiated  or  overlooked :  Moli^re, 
Descartes,  Pascal,  Diderot,  the  two  Rousseaus,  Beaumarchais, 
Balzac,  Beranger,  the  Goncourts,  Daudet,  Emile  Zola,  and 
many  other  extremely  gifted  people,  whom  it  should  reaUy 
have  been  able  to  find. 

The  only  true,  and  at  the  same  time  necessary  as  well  as 
sufficient,  breeding  is  carried  out  by  Nature  herself  in  con- 
junction with  social  conventions,  which  promise  the  more 
success  the  less  they  assume  the  character  of  incubators 
and  breeding  estabUshments.  If  you  wish  to  apply  tests  to 
discover  pupils  of  genius  in  any  class,  examine  as  much  as 
you  Hke,  excite  interest  and  ambition,  distribute  prizes  even, 
but  not  for  the  purpose  of  separating  at  short  intervals  the 
shrewd  and  needle-witted  heads  from  the  rest ;  and  do  not 
lose  sight  of  the  fact  that  among  those  who  appear  as  the 
sheep  as  a  result  of  these  systematized  tests  to  discover  in- 
genuity there  are  many  who,  ten  or  twenty  years  later,  will 
take  up  their  positions  as  men  of  eminent  talent. 

There  is  no  essential  difference  between  the  forced  promo- 
tion of  such  pupils  and  the  breeding  of  super-men  according 
to  Nietzsche's  recipe  as  exemphfied  by  his  Zarathustra. 


84  EINSTEIN  THE  SEARCHER 

Assuming  that  super-men  are  justified  in  existing  at  all, 
they  will  come  about  of  themselves,  but  cannot  simply  be 
manufactured.  Workmen,  taken  as  a  class,  represent  super- 
men more  definitely  than  an  individual  such  as  Napoleon 
or  Caesar  Borgia.  So  the  "  super-scholar  "  exists  perhaps 
already  to-day,  not  as  an  individual  phenomenon,  but  as  a 
whole,  representing  his  class.  Whoever  has  had  experience 
in  these  things  will  know  that  nowadays  there  are  difficult 
subjects  in  which  it  is  possible  to  apply  to  pupils  of  fifteen 
years  of  age  tests  that  are  far  above  the  plane  of  comprehen- 
sion of  pupils  of  the  same  age  in  former  times,  provided  that 
the  average  is  considered,  that  no  accidental  or  artificial 
separation  has  occurred,  that  no  pretentiously  witty  questions 
have  had  to  be  answered,  and  that  there  has  been  no  systematic 
and  inquisitive  search  for  talent. 

Let  us  rest  satisfied  if  we  find  that  the  sum-total  of  talent 
is  continually  on  the  increase.  On  the  other  hand,  it  is  by 
no  means  proved  that  we  are  doing  civiHzation  a  service  by 
persisting  in  the  impossible  project  of  abolishing  from  the 
world  the  struggle  for  existence  prescribed  by  Nature.  It  is 
an  elementary  fact,  and  one  that  is  easy  to  understand,  that 
many  talents  perish  unnoticed.  On  the  other  hand,  observe 
the  long  Ust  of  eminent  men  who  fought  their  way  upwards 
out  of  the  lowest  stages  of  existence  only  to  recognize  that  the 
difficulties  that  have  been  overcome  are  mostly  necessary 
accompaniments  of  talent,  that  is,  that  Nature's  way  of 
selection  is  to  oppose  obstacles  and  raise  difficulties  in  order 
to  test  their  powers.  In  the  case  of  the  poor  lens-grinder 
Spinoza  and  many  others  ranging  to  Beranger,  who  was  a 
waiter,  what  a  chain  of  desperate  experiences,  yet  what 
triumphs  !  Herschel,  the  astronomer,  was  too  poor  to  buy 
a  refracting  telescope,  and  it  was  just  this  dispensation  of 
poverty  that  made  him  succeed  in  constructing  a  reflecting 
type  composed  of  a  mirror.  Faraday,  the  son  of  a  blacksmith 
without  means,  made  his  way  for  years  as  a  bookbinder's 
apprentice.  Joule,  one  of  the  founders  of  the  mechanical 
theory  of  heat,  started  as  a  beer-brewer.  Kepler,  the  dis- 
coverer of  the  planetary  laws,  was  descended  from  a  poverty- 
stricken  innkeeper.  Of  the  members  in  Goethe's  circle, 
Jung-Stilling,  of  whom  Nietzsche  was  so  fond,  was  a  tailor's 


EDUCATION  85 

apprentice ;  Eckermann,  (k)ethe's  intimate  associate,  was  a 
swine-herd,  and  Zelter  was  a  mason.  We  could  add  many 
recent  names  to  this  list,  and  very  many  more  if  we  continue 
the  line  backwards  to  Euripides,  whose  father  was  a  publican 
and  whose  mother  was  a  vendor  of  vegetables.  This  might 
serve  as  a  basis  for  many  reflections  about  the  *'  upward  course 
of  the  talented,"  and  about  its  less  favourable  reverse  side. 
For  one  might  put  the  apparently  paradoxical  question  whether 
a  soaring  career  for  many  or  all  talents  is  a  necessity  for  our 
civilization,  or  whether  it  would  not  be  better  to  have  a  sub- 
stratum interspersed  with  talent,  to  cultivate  a  mossy  under- 
growth which  is  to  serve  as  nourishment  for  the  blooming 
plants  of  the  upper  layer. 

Maximum  is  not  equivalent  to  optimum,  and  we  learned 
elsewhere  that  Einstein  is  far  removed  from  identifying  them. 
In  the  previous  case  it  was  a  question  of  the  problem  of  popu- 
lation ;  and  in  the  course  of  the  discussion  he  mentioned  that 
we  are  subject  to  an  old  error  of  calculation  when  we  regard 
it  as  a  desirable  aim  to  have  a  maximum  number  of  himian 
beings  on  the  earth.  It  seems,  indeed,  that  this  false  con- 
clusion is  already  in  process  of  being  corrected.  A  beginning 
is  being  made  with  new  and  very  active  organizations  and 
unions  whose  programme  is  to  reduce  the  number  so  that  an 
optimum  may  be  attainable  by  those  left. 

If  we  extend  this  line  of  reasoning  still  further,  we  arrive 
at  the  depressing  question  whether  too  much  might  not  be 
done  for  talent,  not  only  as  regards  breeding  it,  but  also  in 
favouring  the  greatest  number.  It  is  quite  possible  that  in 
doing  so,  we  might  overlook,  or  take  insufficient  account  of 
the  harm  that  might  be  done  to  the  lower  stratum,  in  that 
we  should  be  depriving  it  of  forces  which,  according  to  the 
economy  of  Nature,  should  remain  and  act  in  concealment. 

This  fear,  as  here  expressed,  is  not  shared  by  Einstein. 
However  brusquely  he  repudiates  breeding,  he  speaks  in 
favour  of  smoothing  the  way  for  talent.  "  I  believe,"  he  said, 
**  that  a  sensible  fostering  of  gifts  is  of  advantage  to  humanity 
generally  and  prevents  injustice  being  done  to  the  individual. 
In  great  cities  which  give  such  lavish  opportunities  of  educa- 
tion, this  injustice  manifests  itself  less  often ;  but  it  occurs 
so  much  the  more  in  rural  districts,  where  there  are  certainly 


86  EINSTEIN  THE  SEARCHER 

many  cases  of  gifted  youths  who,  if  recognized  as  such  at  the 
right  age,  would  attain  to  an  important  position,  but  who, 
together  with  their  gifts,  become  stunted,  nay,  go  to  ruin,  if 
the  principle  of  selection  does  not  penetrate  to  their  circle." 

This  brings  us  to  the  most  difficult  and  most  dangerous 
point.  The  spectre  of  responsibiUty  is  rapping  at  the  portals 
of  society,  and  is  reminding  us  insistently  that  it  is  our  duty 
to  see  that  no  injustice  be  done  to  any  talent  that  may  be  among 
us.  And  this  duty  is  but  Uttle  removed  from  the  demand  that 
it  should  be  disburdened  of  the  worries  of  daily  Ufe,  for,  so 
the  moral  argument  runs,  talent  will  ripen  the  more  surely  the 
less  it  has  to  combat  these  ceaseless  disturbances  of  ordinary 
hfe. 

But  this  thesis,  so  evident  on  moral  grounds,  will  never  be 
proved  empirically.  On  the  contrary,  we  have  good  reason  to 
suppose  that  necessity,  the  mother  of  invention  on  the  broader 
scale,  will  often  in  the  case  of  the  individual  talent  prove  to  be 
the  mother  of  its  best  results.  Goethe  required  for  his  develop- 
ment an  unchallenged  life  of  ease,  whereas  Schiller,  who  never 
emerged  from  his  hfe  of  misery,  and  who,  up  to  the  time  when 
he  wrote  Don  Carlos,  had  not  been  able  to  earn  sufficient  with 
his  pen  to  buy  a  writing-desk,  required  distress  to  make  his 
genius  burst  into  flower.  Jean  Paul  recognized  this  blessing 
of  gloomy  circumstances  when  he  glorified  poverty  in  his 
novels.  Hebbel  followed  him  along  this  path  by  saying  that  it 
is  more  fruitful  to  refuse  the  most  talented  person  the  necessities 
of  Ufe  than  to  grant  them  to  the  least  gifted.  For  among 
a  hundred  who  have  been  chosen  by  the  method  of  sifting, 
there  will  be  only  one  on  the  average  who  will  receive  the 
certificate  of  excellence  in  the  test  of  future  generations,  for 
the  latter  use  entirely  diflEerent  methods  of  sifting  from  that 
practised  by  a  committee  of  examiners  who  expect  ready 
answers  to  prepared  questions. 

This  projects  us  on  to  the  horns  of  a  severe  dilemma  that 
scarcely  allows  of  escape.  The  consciousness  of  duty  towards 
the  optimum  expresses  itself  only  in  a  maximum  of  assistance, 
and  overhears  the  whispered  objection  of  reason  that  Nature 
has  also  coarser  means  at  her  disposal  to  attain  her  ends; 
in  her  own  cruelty  of  selection  she  often  enough  proves 
the  truth  of  Menander's   saying,   which,  freely   translated. 


EDUCATION  87 

says:  to  be  tormented  is  also  part  of  man's  education. 
The  fact  that  Einstein — with  certain  reservations — favours 
the  giving  of  help  to  the  selected  few,  it  is  for  me  a  proof, 
among  many  others,  of  his  love  towards  his  fellow-men,  which 
fills  his  heart  absolutely,  all  questions  of  relativity  notwith- 
standing. 


CHAPTER  V 
THE  DISCOVERER 

Relation  of  Discovery  and  Philosophy  in  History. — ^The  Absolute  and  the 
Relative. — The  Creative  Act. — Value  of  Intuition. — Constructive  Activity. — 
Invention. — The  Artist  as  Discoverer. — Theory  and  Proof. — Classical  Ex- 
periments.— Physics  in  Primitive  Ages. — Experimentum  Cruets. — Spectral 
Analysis  and  Periodic  System. — The  Role  of  Chance. — Disappointed  Expecta- 
tions.— ^The  Michelson-Morley  Experiment  and  the  New  Conception  of  Time. 

NEXT  time — so  one  of  our  talks  ended — ^next  time,  as 
you  insist  on  it,  we  shall  talk  of  discovery  in  general. 
This  was  a  promise  of  special  import  for  me,  for  it 
meant  that  I  was  to  draw  near  to  a  fountain-head  of  instruction, 
and  to  have  an  opportunity  of  hearing  the  pronouncements 
of  one  whose  authority  could  scarcely  be  transcended. 

We  are  precluded  from  questioning  GaHlei  personally  about 
the  foundations  of  Mechanics,  or  Columbus  about  the  inner 
feelings  of  a  navigator  who  discovers  new  lands,  or  Sebastian 
Bach  about  the  merits  of  Counterpoint,  but  a  great  discoverer 
lives  among  our  contemporaries  who  is  to  give  us  a  clue  to  the 
nature  of  discovery.  Was  it  not  natural  that  I  should  feel  the 
importance  of  his  acceptance  of  my  proposal  ? 

Before  meeting  him  again  I  was  overwhelmed  with  ideas 
that  arose  in  me  at  the  sHghtest  echo  of  the  word  "  discovery  '* 
in  my  mind.  Nothing,  it  seemed  to  me,  could  be  higher  : 
man's  position  in  the  sphere  of  creation  and  the  sum  of  his 
knowledge  can  be  deduced  from  the  sum  of  his  discoveries 
which  find  their  chmax  in  the  conceptions  civilization  and 
philosophy,  just  as  they  are  partly  conditioned  by  the 
philosophy  of  the  time.  We  might  be  tempted  to  ask : 
which  of  these  two  precedes,  and  which  follows  ?  And 
perhaps  the  ambiguous  nature  of  this  question  would  furnish 
us  with  the  key  to  the  answer.  For,  ultimately,  these  two 
elements  cannot  at  all  be  resolved  into  the  relationship  of 
cause  and  effect,  antecedent  and  consequent. 


THE  DISCOVERER  89 

Neither  is  primary,  and  neither  secondary :  they  are  in- 
timately interwoven  with  one  another,  and  are  only  different 
aspects  of  one  and  the  same  process.  At  the  root  of  this  process 
is  our  axiomatic  belief  that  the  world  can  be  comprehended, 
and  the  indomitable  will  of  all  thinking  men,  acting  as  an 
elementary  instinct,  to  bring  the  perceptual  events  in  the 
universe  into  harmony  with  the  inner  processes  of  thought. 
This  impulse  is  eternal ;  it  is  only  the  form  of  these  attempts 
to  make  the  world  fully  intelligible  that  alters  and  is  subject 
to  the  change  of  time.  This  form  finds  expression  in  the 
current  philosophy  which  brings  each  discovery  to  fruition, 
just  as  philosophy  bears  in  itself  constituents  of  the  ripe 
discovery. 

It  seemed  to  me  that  even  at  this  stage  of  my  reflections  I 
was  somewhere  near  interpreting  Einstein's  intellectual  achieve- 
ment. For  his  principle  of  relativity  is  tantamount  to  a  regu- 
lative world-principle  that  has  left  a  mighty  mark  in  the  thought 
of  our  times.  We  have  lived  to  see  the  death  of  absolutism  ; 
the  relativity  of  the  constituents  of  pohtical  power,  and  their 
mutabiUty  according  to  view-point  and  current  tendencies, 
become  manifest  to  us  with  a  clearness  unapproached  by  any 
experience  of  earher  historical  epochs.  The  world  was  far 
enough  advanced  in  its  views  for  a  final  achievement  of  thought 
which  would  demolish  the  absolute  also  from  the  mathematico- 
physical  aspect.  This  is  how  Einstein's  discovery  appeared 
as  inevitable. 

Yet  a  shadow  of  doubt  crossed  my  mind.  Einstein's 
discoveries  came  to  hght  in  the  year  1905 — that  is,  at  a  time 
when  hardly  a  cloud  was  visible  to  forewarn  us  of  the  storms 
which  were  to  uproot  absolutism  in  the  world.  But  what  if  a 
different  kind  of  necessity  had  imposed  itself  on  world-history, 
and  hence  on  the  world-view  ?  Nowadays  we  know  from 
authentic  accounts,  which  no  one  doubts,  that  all  that  we  have 
experienced  during  the  war  and  the  revolution  has  hung  upon 
the  activities  of  one  frail  human  being  of  quite  insignificant 
exterior,  a  bureaucrat  of  the  Wilhelm-Strasse,  a  choleric  eccen- 
tric who  succeeded  in  frustrating  the  Anglo-German  alhance 
which  was  unceasingly  being  pressed  upon  us  for  six  long 
years  after  the  beginning  of  the  century. 

Amid  the  noisy  progress  of  universal  evolution  the  secret 


90  EINSTEIN  THE  SEARCHER 

and  insignificant  nibbling  of  a  mole  cannot  be  regarded  as  of 
momentous  importance  for  history,  and  yet  if  we  eliminate  it 
from  the  complete  picture  of  events  we  find  as  a  result  that  all 
our  experiences  have  been  inverted.  Absolutism  would  not 
have  been  thrown  overboard,  but  would  probably  have  kept 
the  helm  with  greater  mastery  than  ever  as  the  exponent  of  an 
Anglo-German  hegemony  of  the  world,  and  a  pohtical  outlook 
fundamentally  difiPerent  in  tendency  would  now  have  been 
prevailing  on  the  earth. 

But  Einstein's  Theory  of  Relativity  would  not  have  taken 
the  slightest  heed  of  this.  It  would  have  arisen  independently 
of  the  current  forms  of  pohtical  conceptions,  simply  because 
we  had  reached  that  point  in  our  intellectual  development  and 
because  Einstein  was  living  and  spinning  his  webs  of  thought. 
And  the  question  whether  his  theory  will  also  have  crushed 
absolutism  for  the  non-physicist  cannot  be  answered. 

It  may  indeed  be  doubted  whether  its  time  had  already 
come.  In  the  case  of  many  important  events  in  the  history  of 
thought  their  moment  of  birth  can  be  fixed  to  within  about 
ten  years,  as  for  example  the  Theory  of  Evolution,  which  had 
been  conceived  in  several  minds  at  the  same  time  and  had  of 
necessity  to  come  to  Hfe  in  one  of  them,  even  if  it  had  failed  in 
the  case  of  the  others.  I  venture  to  say  that  without  Einstein, 
the  Theory  of  Relativity  in  its  widest  sense,  that  is,  including 
the  new  doctrine  of  gravitation,  would  perhaps  have  had  to 
wait  another  two  hundred  years  before  being  born. 

This  contradiction  is  cleared  up  if  we  use  sufficiently  great 
time  intervals.  History  does  not  adapt  itself  to  the  time 
measures  of  poUtics  and  of  journaHsm,  and  philosophies  are 
not  to  be  calculated  in  terms  of  days.  The  philosophy  of 
Aristotle  held  sway  right  through  the  Middle  Ages,  and  that 
of  Epicurus  will  gain  its  full  force  only  in  the  coming  genera- 
tion. But  if  we  make  our  unit  a  hundred  years  the  connexion 
between  philosophies  and  great  discoveries  remains  true. 

Whoever  undertakes  to  explore  the  necessity  of  this  con- 
nexion cannot  evade  the  fact  that  the  fines  of  the  result  had 
been  marked  out  in  the  region  of  pure  thought,  as  can  be  proved, 
before  even  the  great  discovery  or  invention  was  able  to  present 
it  in  a  fully  intelHgible  form.  Even  the  achievement  of  Coper- 
nicus would  follow  this  general  rule  of  development :   it  was 


THE  DISCOVERER  91 

the  last  consequence  of  the  behef  in  the  Sun  Myth  which  had 
never  been  forsaken  by  man  in  spite  of  the  violent  efforts  of 
the  Church  and  of  man  himself  to  force  the  geocentric  view. 
Copernicus  concentrated  what  had  survived  of  the  wisdom  of 
the  earliest  priests — which  includes  also  the  germ  of  our  modem 
ideas  of  energy  and  electricity — of  the  teachings  of  Anaxagoras 
and  the  Eleatics  which  had  remained  latent  in  our  conscious- 
ness :  his  discovery  was  the  transformation  of  a  myth  into 
science.  Mankind,  whose  wandering  fancy  first  feels  pre- 
sentiments, then  thinks  and  wishes  to  know,  is  a  large  edition 
of  the  individual  thinker.  The  latter  sees  further  only  because 
he,  so  to  speak,  stands  on  the  shoulders  of  a  sum-total  of  beings 
with  a  world-view. 

Let  us  turn  our  attention  to  an  example  from  the  most 
recent  history  of  philosophy  and  discovery.  The  absolute 
continuity  of  events  was  one  of  the  generally  accepted  canons 
of  thought,  and  is  even  nowadays  taught  by  serious  philo- 
sophers as  an  incontrovertible  element  in  our  knowledge.  The 
old  quotation  Natura  non  facit  saltus,  popularized  by  Linne, 
is  one  of  the  formulae  of  this  apparently  invincible  truth.  But 
deep  down  in  the  consciousness  of  man  there  has  always  been 
an  opposition  to  it,  and  when  the  French  philosopher  Henri 
Bergson  set  out  to  break  up  this  line  of  continuity  by  meta- 
physical means  in  ascribing  to  human  knowledge  an  inter- 
mittent, cinematographic  character,  he  was  proclaiming  in  an 
audible  and  eloquent  form  only  what  had  lain  latent  in  a  new 
but  as  yet  incomplete  philosophy.  Bergson  made  no  new 
"  discovery,"  he  felt  his  way  intuitively  into  a  new  field  of 
knowledge  and  recognized  that  the  time  was  ripe  for  the  real 
discovery.  This  was  actually  presented  to  us  in  our  day  by 
the  eminent  physicist  Max  Planck,  the  winner  of  the  Nobel 
Prize  for  Physics  in  1919,  in  the  form  of  his  "  Quantum  Theory." 
This  is  not  to  be  taken  as  meaning  that  a  revolutionary  philo- 
sophy and  a  triumph  of  scientific  research  now  become  co- 
incident, but  only  that  a  discontinuous,  intermittent  sequence, 
an  atomistic  structure,  was  proved  by  means  of  the  weapons 
of  exact  science,  to  be  true  of  energies  which,  according  to 
current  behef,  were  expected  to  be  radiated  regularly  and 
connectedly.  This  was  probably  not  a  case  of  the  accidental 
coincidence  of  a  new  philosophical  view  with  the  results  of 


92  EINSTEIN  THE  SEARCHER 

reasoning  from  physical  grounds,  but  a  demand  of  time,  exact- 
ing that  the  claims  of  a  new  principle  of  thought  be  recognized. 

As  above  suggested,  it  is  more  difficult  to  find  a  fink  between 
Einstein's  discoveries  and  antecedent  presentiments  of  rela- 
tivity. For  a  mere  reference  to  the  downfall  of  absolutism 
in  the  world  of  human  events  will  not  suffice.  In  the  case  of 
Einstein,  we  see  such  a  tremendous  rush  of  thought  in  one 
being  that  we  almost  feel  compelled  to  recognize  an  analogy 
with  the  Quantum  Theory  and  believe  in  a  discontinuity  in  the 
course  of  intellectual  history.  Yet  there  are  certainly  threads 
that  connect  Einstein's  achievement  with  a  prophetic  insight. 
In  this  case,  however,  we  must  spread  out  over  centuries  what 
in  the  case  of  other  discoveries  extends,  in  comparison,  only 
over  decades.  That  doubt  of  Faust,  which  troubles  the  spirit 
of  every  thinker :  **  whether  in  yonder  spheres  there  is  also  an 
Above  and  a  Below,'*  and  which  goes  back  as  far  as  Pyrrhon 
and  Protagoras,  is  itself  relativistic ;  it  expresses  doubt  whether 
the  co-ordinate  system  passing  through  our  own  lives  as  centres 
is  vahd.  It  is  ultimately  a  matter  of  point  of  view,  and  the 
mathematico-physical  consequences  of  the  endless  series  of 
questions,  and  the  relation,  which  arises  from  the  couple, 
Above-Below,  probably  leads  to  a  new  mode  of  comprehending 
the  constitution  of  the  world,  for  which  Einstein's  creative 
work  found  the  adequate  expression  in  abstract  terms.  And 
from  this  point  onwards,  in  accordance  with  the  principle  of 
reciprocal  action,  a  new  stream  of  knowledge  will  pour  itself 
into  the  hazy  stretches  of  philosophy.  A  fundamental  and 
radical  reform  of  our  philosophy  seems  inevitable,  particularly 
with  respect  to  our  conceptions  of  Space  and  Time,  perhaps, 
too,  even  with  respect  to  Infinity  and  Causahty.  Much  dross 
will  have  to  be  sifted  out  of  our  old  categories  of  thought  and 
out  of  our  world  wisdom,  which  once  served  as  material  for  fine 
structures.  What  will  the  finer  ones  look  Hke  that  are  to  take 
their  places  in  obedience  to  the  command  of  physics  ?  Who 
would  care  to  take  it  upon  himself  to  form  an  estimate  ? 

Much  will  be  uprooted,  and  it  is  possible  that  even  the 
defiant  '*  ignorabimus,"  the  antipole  of  the  search  for  truth 
from  Pyrrhon  to  Dubois,  will  again  take  up  the  cudgel.  For 
in  the  face  of  despairing  uncertainty  there  is  the  one  certainty  : 
what  cannot  be  comprehended  is  being  encircled  more  and  more 


THE  DISCOVERER  98 

by  the  great  discoverers  !  And  even  if  the  absolute  point  of 
convergence  can  never  be  reached,  there  is  within  our  reach  at 
least  another  point  which  is  a  haven  of  rest  in  the  passing 
stream  of  philosophies,  namely,  a  moral  centre  around  which 
eddies  of  happiness  circle.  At  the  heart  of  this  world- view 
there  is  the  upHfting  behef  in  an  advance  of  knowledge  in 
spite  of  all,  and  a  behef  in  the  vanishing  of  age-long  problems 
and  difficulties  under  the  flood  of  discoveries.  And  even  if 
afterwards  and  concurrently  ever  new  problems  and  diffi- 
culties arise,  these  do  not  suppress  our  feehng  of  triumph. 
Every  achievement  in  this  field  gives  us  a  sense  of  enfranchise- 
ment from  prejudices,  not  the  least  of  which  is  narrowness  of 
national  outlook.  Not  only  do  discoverers  construct  bridges 
of  thought  that  stretch  to  astronomical  distances,  but,  what  is 
more  difficult,  they  build  bridges  for  our  feeUngs,  that  sur- 
mount poUtical  obstacles.  Every  thinking  being  who  plays  a 
part  in  the  making  of  some  great  discovery  and  who,  with 
deepened  vision,  bows  before  a  new  achievement  of  mind, 
gradually  becomes  a  disciple  of  the  reUgion  of  universal 
poUtics,  the  creed  of  which  is  faith  in  the  brotherhood  of 
thought.  The  nucleus  of  a  philosophy  that  belongs  to  the 
future  is  the  recognition  that  differing  national  view  must  be 
compounded  into  a  unity,  and  that  every  great  discovery 
means  a  step  towards  attaining  this  end. 

Even  if  we  accept  Pascal's. wonderful  dictum  that  human 
knowledge  is  represented  by  a  sphere  which  is  continually 
growing  and  increasing  its  points  of  contact  with  the  imknown, 
we  must  not  interpret  it  as  a  sign  of  despair.  It  is  not  the 
enlargement  of  the  unknown,  but  only  that  of  knowledge  that 
stirs  our  feehngs  with  ethical  forces.  The  positive  calls  up  in 
us  a  Uving  force  by  inspiring  in  us  the  feehng  that  the  sphere 
of  knowledge  is  destined  to  grow,  and  that  there  can  be  no 
higher  duty  for  all  the  energies  of  mind  than  to  obey  the  call 
for  combined  action  towards  this  growth  which  will  bring  the 
world  into  harmony. 

Full  of  such  reflections  I  entered  the  home  of  the  great 
discoverer,  whose  activities  imceasingly  hovered  before  my 
vision  as  ideal  examples  of  creative  effort.  I  discovered  him, 
as  almost  always,  seated  before  loose  sheets  of  paper  which  his 
hand  had  covered  with  mathematical  symbols,  with  hiero- 


94  EINSTEIN  THE  SEARCHER 

glyphics  of  that  universal  language  in  which,  according  to 
Galilei,  the  great  book  of  Nature  is  written. 

What  a  very  different  picture  many  an  outsider  draws  of 
the  manner  in  which  a  seeker  in  the  heavens  works  !  He  is 
imagined  like  Tycho  Brahe  to  be  surrounded  by  unusual 
pieces  of  apparatus,  spying  through  the  ocular  of  a  long  range 
refractor  into  the  universe,  seeking  to  unravel  its  ultimate 
secrets.  The  true  picture  does  not  correspond  to  this  fancy 
in  the  slightest.  Nothing  in  the  make-up  of  the  room  reminds 
one  of  super-earthly  sublimity,  no  abundance  of  instruments 
or  books  is  to  be  seen,  and  one  soon  becomes  aware  that  here 
a  thinker  reigns  whose  only  requirement  for  his  work,  which 
encompasses  the  world,  is  his  own  mind,  plus  a  sheet  of  paper 
and  a  pencil.  All  that  acts  on  the  observatories  outside,  that 
gives  rise  to  great  scientific  expeditions,  that,  indeed,  ulti- 
mately regulates  the  relationship  of  mankind  to  the  con- 
stitution of  the  universe,  the  revolution  in  the  knowledge  of 
things  connecting  heaven  and  earth,  all  this  is  here  con- 
centrated in  the  simple  figure  of  a  still  youthful  scholar,  who 
spins  out  endless  threads  from  the  fabric  of  his  mind  :  the 
words  of  a  poet  are  recalled  to  our  memory,  which,  addressed 
to  all  of  us,  have  been  fulfilled  to  the  last  degree  by  one  living 
among  us  : — 

"  Whereso  thou  roamest  in  space,  thy  Zenith  and  Nadir  unite  thee — 
This  to  the  heavenly  height,  that  to  the  pole  of  the  world, — 
Whatsoever  thou  do,  let  thy  will  mount  up  into  Heaven — 
But  let  the  pole  of  the  world  still  o'er  thine  actions  preside." 

(Schiller  :  Translation  by  Merivale.) 

And  this  one  helped  to  fulfil  this  aim  and  I  must  break  oft 
his  thread  of  thought  to  put  the  question  :  What  is  Discovery, 
and  what  does  it  signify  ? 

It  is  a  purely  abstract  question  that  may  appear  to  many 
to  be  devoid  of  content.  Such  will  repeat  to  themselves,  as 
best  they  can,  the  hst  of  discoveries  and  think  a  man  makes 
a  discovery  when  he  finds  out  something  important,  such  as 
the  Laws  of  Falling  Bodies,  the  formation  of  Rainbows,  or  the 
Origin  of  Species  :  a  general  denomination  may  be  found  for 
it  perhaps  only  by  ascribing  to  Discovery  something  requiring 
a  powerful  mind,  a  creative  genius. 

At  first  it  staggered  me  to  hear  Einstein  say  :   "  The  use  of 


THE  DISCOVERER  95 

the  word  '  Discovery '  in  itself  is  to  be  deprecated.  For 
discovery  is  equivalent  to  becoming  aware  of  a  thing  which  is 
already  formed  ;  this  links  up  with  proof,  which  no  longer 
bears  the  character  of  *  discovery '  but,  in  the  last  instance,  of 
the  means  that  leads  to  discovery."  He  then  stated  at  first 
in  blimt  terms,  which  he  afterwards  elaborated  by  giving  de- 
tailed illustrations  :  "  Discovery  is  really  not  a  creative  act !  " 

Arguments  for  and  against  this  view  flashed  through  my 
mind,  and  I  thought  involuntarily  of  a  great  master  of  music 
who,  when  he  was  asked  :  *'  What  is  Genius  ?  "  answered  : 
'*  A  genius  is  one  to  whom  ideas  occur."  This  parallel  might 
be  carried  still  further,  for  I  have  repeatedly  heard  Einstein 
call  "  ideas  "  what  we  would  regard  as  wonderful  thoughts. 
Does  not  the  philosopher  Fritz  Mauthner  speak  of  the  discovery 
of  gravitation  as  being  an  "  apergu  "  of  Newton  ;  yes,  in  the 
sense  of  aperfus  as  appHed  in  ancient  Greek  philosophy,  and 
which  included  almost  everything  that  was  left  by  Pythagoras, 
HeracHtus,  etc.,  as  a  token  of  their  genius.  On  the  other  hand, 
we  are  all  possessed  of  the  desire  to  differentiate  clearly 
between  an  idea  and  a  creative  act  of  thought,  as  occurs  in 
Grillparzer's  aphorism  :  **  An  idea  is  not  a  thought ;  a  thought 
knows  its  bounds,  whereas  the  idea  leaps  over  them  and 
succeeds  in  accompHshing  nothing  1  " 

Here,  then,  we  must  revise  our  view.  We  know,  for  ex- 
ample, how  much  Einstein's  "  ideas,"  felt  by  him  to  be  such 
and  named  so  accordingly,  accompUshed.  Let  us  hear  how 
he  characterizes  in  a  few  words  his  own  "  idea  "  which  shook 
the  world  : 

"  The  underlying  thought  of  relativity,"  he  said,  in  con- 
nexion with  this  question,  "  is  that  there  is  physically  no 
unique  (specially  favoured)  state  of  motion.  Or,  more  exactly, 
among  all  states  of  motion  there  is  none  that  is  favom-ed  in 
the  sense  that,  in  contradistinction  to  the  others,  it  may  be 
said  to  be  a  state  of  rest.  Rest  and  Motion  are  not  only  by 
formal  definition  but  also  by  their  intrinsic  physical  meaning 
relative  conceptions.*' 

"  Well,  then,"  I  interposed,  "  surely  this  was  a  creative 
act !  This  first  flashed  across  your  mind.  Professor ;  it  re- 
presents your  discovery,  so  that  we  may  well  let  the  word 
retain  the  meaning  usually  associated  with  it !  " 


96  EINSTEIN  THE  SEARCHER 

"  By  no  means,"  answered  Einstein,  *'  for  it  is  not  true 
that  this  fundamental  principle  occurred  to  me  as  the  primary 
thought.  If  this  had  been  so  perhaps  it  would  be  justifiable 
to  call  it  a  "  discovery."  But  the  suddenness  with  which 
you  assume  it  to  have  occurred  to  me  must  be  denied.  Actu- 
ally, I  was  lead  to  it  by  steps  arising  from  the  individual  laws 
derived  from  experience." 

Einstein  supplemented  this  by  emphasizing  the  conception 
"  invention,"  and  ascribed  a  considerable  importance  to  it  : 
"  Invention  occurs  here  as  a  constructive  act.  This  does  not, 
therefore,  constitute  what  is  essentially  original  in  the  matter, 
but  the  creation  of  a  method  of  thought  to  arrive  at  a  logically 
coherent  system  .  .  .  the  really  valuable  factor  is  intuition  !  " 

I  had  thought,  long  and  intently,  about  these  theses  to 
discover  as  nearly  as  possible  what  distinguished  their  content 
from  the  usual  view.  The  fundamental  differences  suggest 
an  abundance  of  ideas  whose  importance  grows  in  value  as 
we  apply  them  to  various  cases  as  illustrations.  And  I  feel 
convinced  that  we  shall  yet  have  to  occupy  ourselves  with 
these  words  of  Einstein,  which  present  themselves  as  a  con- 
fession, as  with  the  famous  "  hypotheses  non  fingo  "  that 
Newton  set  up  as  the  idea  underlying  his  work. 

The  latter  as  well  as  the  former  implies  something  negative  : 
it  denies  something.  In  Einstein's  words  there  is  apparently 
a  repudiation  of  the  really  creative  act  in  discovery  ;  he  lays 
stress  on  the  gradual,  methodical  constructive  factors,  not 
omitting  to  emphasize  intuition.  There  is  no  other  course 
open  to  us  but  to  seek  indirectly  a  synthesis  of  these  concep- 
tions, and  to  eliminate  what  is  apparently  contradictory  in 
them. 

I  consider  this  possible  if  we  decide  to  subdivide  the  dis- 
covery into  a  series  of  individual  acts  in  which  succession 
takes  the  place  of  instantaneous  suddenness  The  creative 
factor  may  then  remain  intact ;  indeed,  it  attains  a  still  higher 
degree  of  importance  if  we  imagine  to  ourselves  that  a  series 
of  creative  ideas  must  be  Unked  together  to  make  possible  a 
single  important  discovery. 

The  original  idea  never  springs  fully  equipped  and  armed 
like  Minerva  out  of  the  head  of  its  creator.  And  it  is  wise 
to  bear  in  mind  that  even  Jupiter  had  to  suffer  in  his  head 


THE  DISCOVERER  97 

a  period  of  pregnancy  accompanied  with  great  pain.  It  is 
only  in  the  after-picture  that  Pallas  Athene  appears  with  the 
attribute  of  suddenness.  It  is  the  nature  of  our  myth-building 
imagination  to  leap  over  the  actual  act  of  birth  so  as  to  give 
a  more  brilliant  form  to  the  finished  creation. 

We  feel  great  satisfaction  when  we  learn  that  Gauss,  the 
Prince  of  Mathematicians,  declared  in  one  of  his  valuable 
flashes  of  insight  :  "I  have  the  result,  only  I  do  not  yet  know 
how  to  get  to  it."  For  in  this  utterance  we  see  above  all 
that  he  emphasizes  a  Ughtning-Uke  intuition.  He  has  posses- 
sion of  a  thing,  which  is,  however,  not  yet  his  own,  and  which 
can  only  become  his  own  when  he  has  found  the  way  to  it. 
Is  this  contradictory  ?  From  the  point  of  view  of  elementary 
logic,  certainly ;  but  methodologically,  by  no  means.  Here 
it  is  a  question  of  :  Erwirb  es  um  es  zu  hesitzen  !  This  makes 
necessary  a  series  of  further  intuitions  along  the  road  of 
invention,  and  of  construction. 

This  is,  then,  where  that  phase  commences,  which  Einstein 
denotes  by  the  word  "  gradual,'*  or  "by  steps."  The  first 
intuition  must  be  present ;  its  presence  as  a  rule  usually 
guarantees  that  further  intuition  will  follow  in  logical  sequence 

This  does  not  always  happen.  In  passing,  we  discussed 
several  special  cases  from  which  particular  inferences  may 
be  drawn.  The  powerful  mathematician  Pierre  Fermat  has 
presented  the  world  with  a  theorem  of  extremely  simple  form 
which  he  discovered,  a  proof  of  which  is  being  sought  even 
nowadays,  two  and  a  half  centuries  after  he  stated  it.  In 
easy  language,  it  is  this  :  the  sum  of  two  squares  may  again 
be  a  square,  for  example,  5^-1-122=132,  since  25+144=169; 
but  the  sum  of  two  cubes  can  never  be  a  cube,  and,  more 
generally,  as  soon  as  the  exponent,  the  power  index  n,  is 
greater  than  2,  the  equation  x''-\-y'*  =  z*'  can  never  be  satisfied 
by  whole  number  values  for  x,  y,  and  z  ;  it  is  impossible  to 
find  three  whole  numbers  for  x,  y,  and  z,  which,  when  sub- 
stituted in  the  equation,  give  a  correct  result. 

This  is  certainly  true ;  it  is  an  intuitive  discovery.  But 
Fermat 's  assertion  that  he  possessed  a  "  wonderful  proof," 
is  for  very  good  reasons  open  to  contradiction.  No  one 
doubts  the  absolute  truth  of  the  theorem.  But  the  later 
inspiration,  the  next  step  after  the  intuition,  has  occurred 
7 


98  EINSTEIN  THE  SEARCHER 

neither  to  Fermat  nor  to  anyone  else.  It  cannot  be  established 
whether  his  remark  about  the  proof  was  due  to  a  subjective 
error,  or  was  baseless.  In  any  case  it  seems  probable  that 
Fermat  had  arrived  at  the  result  per  intuitionem  without 
knowing  the  way  to  it.  His  creative  act  stopped  short ;  it 
was  only  a  first  flare  of  a  conflagration,  and  did  not  fulfil 
the  condition  that  Einstein  associates  with  the  conception 
of  a  logically  complete  method. 

We  may,  indeed,  pursue  this  case  of  Fermat  still  further. 
He  had  enunciated  another  theorem,  again  per  intuitionem, 
namely,  that  it  was  possible  to  construct  prime  numbers  of 
any  magnitude  by  a  formula  he  gave.  Euler  later  showed 
by  a  definite  example  that  the  theorem  was  false.  It  was 
stated  in  a  letter  to  Pascal  written  in  1654  in  the  words  :  the 
result  of  squaring  2  continuously  and  then  adding  i  must 
in  each  case  be  a  prime  number,  that  is,  a^^^'  +  i  must  always 
be  a  prime  no  matter  what  value  k  may  have.  Fermat  added  : 
"  This  is  a  property  for  the  truth  of  which  I  answer.'*  Euler 
chanced  to  try  ^=5,  and  found  that  2^^+1=4,294,967,297, 
which  may  be  represented  as  the  product  of  641  and  6,700,417, 
and  hence  is  not  a  prime. 

It  is  conceivable  that  no  Euler  might  have  Uved,  and  that 
no  one  else  might  have  discovered  this  contradiction.  What 
would  then  have  been  the  position  of  this  "  discovery  "  of 
Fermat  ? 

We  should  certainly  not  have  disputed  its  creative  character, 
for  we  should  have  said  that  it  corresponds  to  a  fact  which 
is  fully  formed,  but  cannot  be  proved.  But  now  that  we 
know  that  the  fact  does  not  exist  at  all,  the  thing  assumes  a 
different  colour.  It  was  not  a  discovery  at  all,  but  an  erroneous 
conjecture.  But  one  would  never  be  able  to  arrive  at  an 
erroneous  conclusion  of  this  sort  without  being  a  mathe- 
matical genius,  and  having  the  inspiration  of  the  moment. 
And  from  this  again  it  follows  that  to  make  a  discovery  in 
the  full  sense  of  the  word  the  intuition  of  the  moment  does 
not  suffice,  but  must  be  supported  by  a  series  of  intuitions, 
and  this  is  the  condition  that  it  become  a  permanent  com- 
ponent of  universal  truth. 

The  fact  that  Einstein  refers  to  the  action  of  "  inventing  " 
in  his  explanation,  gives  support,  it  seems  to  me,  to  the  view 


THE  DISCOVERER  99 

that,  strictly  speaking,  discovering  and  inventing  are  never 
to  be  regarded  as  being  separable.  In  discovering,  what  has 
to  be  constructed  persists,  and  in  inventing,  it  is  a  question 
of  finding  the  path  along  which  there  is  the  promise  of  success, 
be  it  by  a  method,  a  proof,  or  by  some  general  work.  We 
spoke  of  works  of  art,  and  I  was  deUghted  to  see  that  Einstein 
was  by  no  means  disinchned  to  claim  certain  works  of  pure 
thought,  which  are  usually  placed  in  the  category  of  scientific 
discovery,  as  works  of  art.  In  the  latter,  however,  the  pure 
process  of  invention  plays  the  prominent  part,  for  in  them 
something  is  represented  that  did  not  exist  at  all  before  ; 
this  has  repeatedly  led  to  the  artist's  achievement  being  given 
the  higher  rank,  as  being  properly  and  exclusively  creative. 
The  argument  runs  somewhat  along  these  Hues  :  the  infinites- 
imal calculus  would  certainly  have  been  discovered  even 
if  there  had  been  no  Newton  and  no  Leibniz,  but  without 
Beethoven  we  should  never  have  had  a  C  Minor  Symphony, 
and  never  in  the  future  would  it  have  appeared,  for  it  was  a 
subjective,  absolutely  personal,  and  unique  product  of  its 
creator. 

I  believe  this  may  be  admitted,  and  that  we  may  neverthe- 
less retain  the  view  that  in  the  work  of  art,  too,  the  act  of 
discovering  is  to  be  found.  Let  us  consider  for  a  moment  the 
elementary  substance  of  the  first  movement  of  this  fifth 
symphony,  a  colossal  movement  of  500  bars,  which  expresses 
itself  quite  definitely  in  four  notes,  of  which  one  is  repeated 
three  times.  "  Thus  Destiny  thunders  at  the  gates "  is 
Beethoven's  motto  for  this  section  ;  it  is  expressed  tonally 
in  a  succession  of  notes  which  through  all  eternity  existed 
among  the  possible  permutative  arrangements  of  these  sounds. 

Beethoven,  so  it  is  expressed,  invented  it.  But  it  is  just 
as  correct  to  say — in  Einstein's  words — "  he  became  aware  of 
what  was  already  formed  " — that  is,  he  "  discovered  "  the 
fundamental  theme,  and  afterwards  "  proved  it  "  in  terms  of 
musical  logic  unheard-of  beauty  in  a  methodical  elaboration. 
We  may,  indeed,  go  further  still.  This  motif  of  four  tones  was 
not  only  extant  as  an  abstractum,  as  a  possible  mathematical 
arrangement,  but  also  as  something  natural.  Czemy,  a 
pupil  of  Beethoven,  to  whom  the  master  confided  many  a 
remark  about  the  origin  of  his  compositions,  reports  that  a 


100  EINSTEIN  THE  SEARCHER 

bird,  the  yellow-hammer,  had  sung  this  theme  to  Beethoven 
in  the  woods.  But  neither  the  bird  nor  any  other  living 
creature  had  invented  it ;  rather  what  could  not  be  created, 
because  it  had  always  been  in  existence,  became  objectified 
in  the  medium  of  sound.  Beethoven  found  it ;  it  was  res 
nullius  when  he  found  it  and  when  he  discovered  simultaneously 
with  the  succession  of  tones  that  they  were  appropriate  for  a 
powerful  musical  representation  of  sombre  Destiny.  Every 
theme,  be  it  of  Beethoven,  Bach,  Wagner,  or  anyone  else,  may 
be  represented  graphically  by  a  curve  (in  the  case  of  Bach's 
fugal  themes  this  has,  in  fact,  been  done  for  special  purposes), 
and  just  as  it  is  certain  that  every  elliptic-arc  existed  before 
all  geometry,  so  it  may  be  affirmed  with  equal  certainty  that 
everything  musical  was  in  existence  before  the  advent  of 
composition,  and  was  merely  waiting  for  a  discoverer  whom 
we  designate  the  inventor,  the  creative  organ. 

But  may  not  some  of  this  glory  be  reflected  on  to  scientific 
discovery  ?  When  we  are  in  an  ecstasy  of  admiration,  we 
talk  of  a  creative  act  as  of  something  divine  ;  may  we  not 
also  grant  to  the  scientist  this  tribute  which,  owing  to  a  slight 
confusion  of  conceptions,  we  shower  on  the  artists  ?  And  I 
beUeve  that  Einstein's  definition  does  not  set  up  an  insuperable 
barrier  in  this  respect  to  our  admiration,  which  exerts  every 
effort  to  pass  beyond,  refuses  to  come  to  a  standstill  before 
the  rigid  fact  that  the  discoverer  reveals  only  what  is  pre- 
formed ;  our  emotions  prove  to  be  stronger  than  our  minds 
with  their  objective  valuation.  In  the  last  instance,  we  opine, 
the  scientific  discoverer,  too,  creates  something  new,  namely,  a 
piece  of  knowledge  that  was  previously  not  in  existence.  And 
we  obey  the  impulse  of  hero-worship,  when  we  call  a  definite 
first  discoverer  a  creator. 

This  silences  opposition  certainly  only  for  a  time,  without 
vanquishing  it.  For  this  knowledge,  too,  lay  ready  before 
the  first  discoverer  appeared  :  he  did  not  create  it,  but  merely 
drew  back  the  veil  that  enveloped  it.  So  that,  ultimately, 
we  get  back  to  ''  intuition  "  in  its  literal  sense,  a  becoming 
aware  of  things,  an  exact  consideration  of  things,  states,  and 
relationships  ;  and  this  intensive  consideration,  full  of  wonder- 
ment, has  always  been  a  privilege  of  a  very  few  chosen  men. 

It  might  be  asked :  Was  there  any  knowledge  of  Pythagoras' 


THE  DISCOVERER  101 

Theorems  before  Pythagoras  gave  us  his  proof  ?  We  should 
have  to  answer :  It  was  in  existence  at  least  in  the  still  dark 
field  of  vision  of  Pythagoras,  which  became  illumined  one 
day  when  he  took  such  a  view  of  the  number-ratios  3 — 4 — 5 
that  an  exact  intuition  could  actually  come  about.  It  is 
erroneous  to  assume  that  a  creative  act  suddailyt-cait^d'  up 
before  his  soul  as  if  by  magic  the  figure  with  the  tfire^  squares 
drawn  externally  on  the  sides  of  a  triangle.  Eatbej.J  he'  '*.  tbol&Cj 
his  stride  "  (as  we  know  from  Vitruvius)  by  cohsiHeiing  a 
triangle  whose  sides  were  of  a  definite  length  ;  and  the  well- 
known  proof,  which  is  linked  indissolubly  in  our  minds  with 
his  work,  is  not  his  at  all,  but  Euclid's.  Yet  our  annals  grow 
musty,  centuries  pass  by,  and  the  credit  of  being  the  creator 
rests  with  the  man  who  first  succeeded  in  getting  a  clear 
picture  of  such  a  triangle. 

It  seems  natural  to  test  discoveries  by  experiments.  The 
first  result  of  doing  this  is  a  very  remarkable  increase  in  the 
rate  at  which  the  intuitive  process  has  developed.  In  ancient 
times,  intuition,  it  seems,  scarcely  felt  the  need  of  proving 
things  by  experiment  ;  all  that  was  discovered  by  Archimedes 
in  mechanics,  by  the  Pythagoreans  in  acoustics,  by  Euclid  in 
optics,  may  be  reduced  practically  to  the  formula  "  heureka," 
and  it  is  probably  scarcely  an  exaggeration  to  say  that  more 
and  more  fruitful  experiments  are  performed  in  one  week 
nowadays  than  in  the  whole  of  the  classical  age  taken  together.* 

*  Recently  certain  precisians  in  definition  have  been  seeking  to  establish 
a  fundamental  difference  between  physicists  of  reality,  experimental  physicists, 
and  "  blackboard-physicists."  The  last  term  is  given  jeeringly  to  theoretical 
physicists  because  they,  in  the  opinion  of  these  critics,  wish  to  found  Nature 
entirely  on  formulae  argued  out  on  the  blackboard.  The  history  of  science 
does  recognize  this  distinction,  although  it  is,  of  course,  quite  possible  for  a 
physicist  to  arrive  at  important  discoveries  without  making  any  experiments. 

One  might  be  more  justified  in  asserting  that  the  great  theorist  need  not 
necessarily  be  a  great  experimenter  and  vice  versa.  But  I  can  quote  no 
example  of  a  physicist  who  confined  himself  obstinately  to  blackboard  dis- 
cussion, and  on  principle  disowned  all  experimental  work. 

I  must  add  that  Einstein  himself  is  fond  of  experimenting,  and  has  had 
much  success  in  experimental  work.  The  amount  of  advice  and  encourage- 
ment that  he  has  given,  and  still  gives,  to  many  workers  in  this  field  is  very 
considerable.  But  he  does  not  practise  experimental  work  regularly,  and 
remarked  that  he  is  obliged  to  appeal  to  outside  help  for  certain  practical  tests. 
There  are  specific  experimental  geniuses,  whose  activity  assumes  the  happiest 
and  most  fruitful  form  when  it  supplements  that  of  the  theorist  and  fertilizes  it. 


102  EINSTEIN  THE  SEARCHER 

Experiments  have  become,  if  not  the  sole,  yet  the  most  definite, 
test  of  intuition.  I  need  only  recall  the  observations  of  the 
solar  eclipse  of  1919,  which  were  of  an  experimental  character 
inasmuch  as  they  used  apparatus  to  question  Nature.  To  the 
world  generally,  they  gave  the  irrefutable  confirmation  of 
Einstein*s  Theory  of  Gravitation,  but  not  to  Einstein  himself, 
whose  intuition  felt  itself  so  certain  that  the  confirmation  was 
a-mere  matter  of  course. 

But  this  is  hot  the  average  case  ;  in  many  cases  the  in- 
tuition of  the  discoverer  appeals  to  experiment  as  a  judge  of 
great  authority,  who  is  to  confirm,  reject,  or  correct. 

Let  us  take  some  examples  of  cases  in  which  the  intensity 
and  the  value  of  intuition  were  measured  by  the  experimental 
results.  Benjamin  FrankHn*s  Kite  Experiment  may  be  taken 
as  a  classical  instance.  Here  is  a  man  in  whose  head  the  idea 
takes  root  that  lightning  and  electricity  are  one  and  the  same 
thing.  Innumerable  persons  before  and  after  his  time  might 
have  hit  on  the  same  idea,  which  is  now  the  common  knowledge 
of  children.  Yet,  a  single  man  had  to  appear  who  became 
aware  of  this  pre-formed  fact  and  who  simultaneously  thought 
out  a  method  of  putting  it  to  proof.  In  1752  he  constructed 
a  kite,  sent  it  up  into  the  clouds  during  a  storm,  and  caught  up 
sparks  on  the  ground  by  a  metalHc  contrivance,  and,  as  d'Alem- 
bert  so  aptly  described  it  to  the  French  Academy : 

"  Eripuit  coelo  fulmen  ..." 

He  wrested  the  lightning  from  the  heavens.  Jupiter  tonans 
illuminated  a  great  discovery,  a  mighty  intuition  which  had 
entered  like  a  lightning  stroke  into  the  brain  of  a  discoverer. 

This  case  would  be  classical,  were  it  not  that  nine-tenths  of 
it  is  based  on  legend.  Franklin  was  by  no  means  the  first  who 
had  this  intuition,  and  his  experimental  test  was  so  full  of 
faults  that  it  was  within  an  ace  of  faiUng.  Frankhn  used  a  dry 
thread  of  hemp,  which  he  thought  to  be  a  conductor,  but 
which  became  a  conductor  only  after  it  had  been  made  wet  by 
rain.  Till  that  moment  the  exhibition  of  sparks  on  the  ground 
had  been  poor  enough,  and  httle  was  wanting  for  Franklin 
to  give  up  his  attempt  and  confess  that  he  had  been  inspired, 
not  with  an  intuition,  but  with  a  hallucination. 

But  to  whom  then  is  the  glory  of  this  discovery  due  ?     This 


THE  DISCOVERER  103 

is  a  difl&cult  point  to  decide.     As  early  as  1746,  that  is,  six  years 

before  Franklin's  kite  made  its  ascent  in  Philadelphia,  Professor 

Winkler  of  Leipzig  had  asserted  in  a  dissertation  that  the  two 

phenomena  were  identical,  and  had  proved  this  theoretically ; 

and  three  years  earlier  still  Abbe  Nollet  had  declared  the 

storm  clouds  to  be  the  conductors  of  an  electrical  induction 

machine.     Almost  simultaneously  with    Frankhn,   DaUbard, 

Delor,  Buffon,  Le  Monnier,  Canton,  Bevis,  and  Wilson  made 

experiments  on  an  elaborate  scale,  which  far  exceeded  that  of 

Frankhn  in  their  results.     To  this  must  be  added  that  the 

experiment  was  conducted  with  evident  success  only  in  1753, 

when  de  Romas  of  Nerac  in  South  France  wove  a  real  conductor 

of  thin  annealed  wire  into  the  kite-string,  and  succeeded  in 

bringing  down  a  regular  thunderstorm  with  flashes  of  hghtning 

ten  feet  long,  accompanied  by  a  deafening  uproar.     It  was  only 

then  that  the  track  of  the  inspiration  was  traced  back  through 

time  to  the  Roman  Kings,  Numa  PompiUus  and  Tullus  Hosti- 

hus,  as  the  first  experimenters  with  hghtning.     And  then  the 

physicist  Lichtenberg  sought  to  furnish  a  proof  that  the  old 

Hebrew  ark  of  the  Covenant,  together  with  the  tabernacle,  were 

nothing  other  than  great  pieces  of  electrical  apparatus  highly 

charged  with  electricity  derived  from  the  air  ;   thus  the  first 

intuition,  and  the  priority  of  discovery,  would  have  to   be 

ascribed  to  Moses  or  Aaron  !     And  connected  with  this  was 

the  fact,  supported  by  substantial  proof,  that  the  Temple  of 

Solomon  was  protected  by  Ughtning-conductors. 

I  must  not  omit  to  mention  that  Einstein  regards  this 
whole  chain  of  proofs  stretching  back  to  early  times  as  by  no 
means  estabUshed,  although  besides  Lichtenberg,  other  im- 
portant scholars,  such  as  Bendavid  in  Berhn  and  Michaelis  in 
Gottingen,  have  vouched  for  their  truth.  And  as  it  is  a  matter 
of  electrical  relationships,  Einstein's  doubts  cannot  be  passed 
over.  As  far  as  I  recollect,  they  were  not  directed  against 
the  rough  facts  in  themselves,  but  against  the  sense  that  is 
construed  into  them — ^that  is  to  say,  in  the  case  of  both  the 
ancient  Roman  and  the  Bibhcal  data,  the  conception  of  dis- 
covery must  be  excluded,  and  must  be  awarded  rather  to  those 
intellectual  efforts  which  have  led  to  the  creation  of  a  method 
of  thought.  None  the  less,  we  may  uphold  our  statement  that 
in  this  case,  presumed  to  be  classical,  neither  Franklin  nor  any- 


104  EINSTEIN  THE  SEARCHER 

one  else  is  to  be  claimed  as  the  discoverer  or  as  the  central 
figure  in  a  creative  act. 

The  experimental  case  of  spectral  analysis  is  incomparably 
simpler  and  less  open  to  dispute.     It  is  without  doubt  a  dis- 
covery of  fundamental  importance  bearing  all  the  character- 
istics of  originality,  for  no  predecessors  are  discernible.    I  have 
always  felt  a  Uttle  dissatisfied  with  the  fact  that  it  required 
two  men  to  think  it  out,  that  a  duo  of  minds  was  necessary  for 
one  act  of  thought  which  appears  quite  uniform,  elementary 
and  inseparable  from  the  intuition  of  a  single  mind.     But  it 
seems  possible  that  tradition  has  not  handed  the  facts  down  to 
us  faithfully,  and  that  the  two  men,  with  a  unanimity  arising 
from  their  partnership  in  work,  combined  their  results,  which 
were  not,  at  the  beginning,  of  a  dual  character.     This  possibility 
became  clear  to  me  from  a  remark  of  Einstein  which  made  it 
plain  to  me  that  the  conjunction  Kirchhoff  and  Bunsen  is  to 
be  taken  as  denoting  Kirchhoff  and  then,  after  a  pause,  Bunsen 
in  the  next  breath  !     But  if  we  discard  this  question  of  unity 
or  duahty,  we  are  left  with  the  fact  that  the  idea  of  a  spectral 
analysis  occurred  to  some  one  (as  a  result  of  preceding  optical 
experiments  with  Fraunhofer  lines),  and  was  fully  confirmed 
by  later  experiments.     Only  fully  confirmed  ?     No,  the  classic 
rank  of  this  case  manifested  itself  in  a  much  more  triumphant 
manner,  for  it  is  impossible  that  the  intuition  of  Kirchhoff 
and  Bunsen  could  have  grasped  the  whole  significance  and 
range  of  their  discovery  even  after  they  had  made  it  their 
own. 

Every  discovery  encloses  a  germ  of  hope.  However  great 
this  may  have  been  in  the  case  of  Kirchhoff,  it  could  not  by  any 
stretch  of  imagination  approach  the  degree  of  its  fulfilment. 
The  fundamental  theoretical  idea  that  "  a  vapour  absorbs  from 
the  ray-complex  of  white  light  only  those  wave-lengths  which 
it  can  emit  *'  gave  rise  to  a  process,  the  ingenuity,  delicacy, 
and  certainty  of  which  is  almost  inconceivable.  When  rays 
of  light  emitted  by  incandescent  vapour  were  separated  by  a 
prism,  there  were  discovered  fine  coloured  fines  that  betrayed 
some  unknown  mystery.  The  spectroscopic  experiments 
proved,  in  a  succession  of  results,  that  the  author  of  the  above 
idea  had  made  not  only  one  discovery,  but  a  whole  host  of  them. 
For  example,  it  was  observed  that,  in  burning  minute  residues 


THE  DISCOVERER  105 

obtained  by  evaporating  certain  mineral  waters,  a  red  line  and 
a  blue  line  that  had  never  been  seen  before  appeared  in  the 
spectrum.  One  knew  immediately  that  an  element,  hitherto 
undiscovered,  was  proclaiming  its  presence.  In  this  way  in 
quick  succession  the  element  Caesium  was  discovered,  then 
Rubidium,  ThaUium,  Indium,  Argon,  Hehum,  Neon,  Krypton, 
Xenon — certainly  things  that  were  already  pre-formed  in 
Nature,  just  as  the  idea  of  a  bridge  from  Optics  to  Chemistry 
lay  all  ready  in  the  heart  of  Nature ;  but  no  blame  can  be 
given  to  the  astonished  contemporaries  who  regarded  this 
fundamental  discovery  of  spectroscopic  analysis  as  a  creative 
achievement  of  the  intellect. 

This  ray  of  hope  gave  a  gHmpse  of  the  degree  of  accuracy 
attainable.  In  this  connexion  the  experiment  confirmed 
infinitely  more  than  the  boldest  imagination  could  ever  have 
dreamed.  A  yellow  fine  was  detected  in  the  spectrum  of 
sodium.  And  it  was  found  experimentally  that  the  three- 
miUionth  part  of  a  thousandth  of  a  gramme  of  a  sodium  salt 
is  sufficient  to  produce  this  sodium  fine  in  the  spectrum  of  a 
Bunsen  burner.  There  commenced  a  dizzying  passage  in  the 
Calculus  of  ProbabiHties  for,  since  it  was  found  that  in  the 
sun's  atmosphere  hydrogen,  carbon,  iron,  aluminium,  calcium, 
sodium,  nickel,  chromium,  zinc,  and  copper  were  present,  the 
question  arose  as  to  how  great  was  the  possibihty  of  an  error 
in  this  observation.  Kirchhoff  calculated  it  as  a  chance  of  a 
trilHon  to  one  that  these  substances  are  actually  present  in 
the  sun  ! 

Never  before  had  an  experiment  verified  to  such  an  extreme 
degree  a  discoverer's  idea.  It  seems  appropriate  at  this  stage 
to  deal  with  a  doctrine  which  seeks  to  shed  fight  into  the  deepest 
recesses  of  the  connexion  between  experiment  and  discovery. 
It  teaches  that  an  experimentum  cruets,  an  experiment  that 
verifies  absolutely,  is  impossible  in  physics.  That  is  to  say, 
every  idea  of  a  discoverer  involves  a  hypothesis,  and,  how- 
ever the  experiment  that  follows  may  turn  out,  there  still 
remains  the  possibihty  that  this  hypothesis  was  false,  and  may 
later  have  to  make  way  for  another  essentially  contradictory 
hypothesis  which  will  be  vafid  again  only  for  a  hmited  time. 

The  chief  exponent  of  this  theory  is  the  eminent  scholar, 
Pierre  Duhem,  Membre  de  I'lnstitut.      He  draws  a  parallel 


106  EINSTEIN  THE  SEARCHER 

between  experiment  and  mathematical  proof,  particularly  with 
the  indirect,  apagogic  form  which  has  been  so  successfully 
appHed  in  EucUdean  geometry.  In  this  method  it  is  assumed 
that  a  certain  statement  is  erroneous  ;  it  is  then  shown  that 
it  leads  to  an  obvious  contradiction  ;  consequently  the  state- 
ment was  correct  provided  that  a  certain  doubt  be  excluded. 
Thus  in  the  domain  of  mathematics  we  have  a  real  experi- 
mentum  cruets. 

In  accordance  with  this,  Duhem  tests  the  vahdity  of  two 
physical  theories,  both  of  which  were  put  forward  and  claimed 
as  discoveries.  Newton  had  discovered  the  nature  of  Hght  to 
consist  in  "  emission  "  ;  to  him,  as  well  as  to  Laplace  and  Biot, 
light  consists  of  projectiles  that  are  emitted  with  very  great 
velocity.  The  discovery  of  Huyghens,  supported  by  Young 
and  Fresnel,  substitutes  wave-motion  in  place  of  corpuscular 
emission.  Hence,  according  to  Duhem,  we  have,  or  we  had, 
here  two  hypotheses  which  appear  to  be  the  only  ones  possible. 
Experiment  was  to  pronounce  a  judgment,  and  at  first  it 
decided  irrefutably  in  favour  of  the  wave-theory.  Therefore, 
the  discovery  of  Huyghens  is  alone  true,  and  that  of  Newton 
is  shown  to  be  an  error ;  there  is  no  third  outlet,  and  so  we 
have  quite  certainly  an  experimentum  cruets  before  us. 

The  term  itself  originates  in  Bacon's  Novum  Organum, 
Contrary  to  Duhem*s  assumption,  it  does  not  refer  to  a  signpost 
at  cross-roads  giving  various  routes,  nor  is  it  connected  with 
croix  ou  pile,  heads  or  tails.  Experimentum  cruets  denotes 
rather  a  divine  judgment  at  the  cross,  that  is  a  test  that  is 
absolutely  decisive  and  beyond  further  appeal.  But  no  !  adds 
Duhem,  there  is  no  room  for  a  third  judgment  in  the  case  of 
two  contradictory  statements  in  geometry,  but  there  is  between 
two  contradictory  statements  in  physics.  And,  in  fact,  this 
third  possibiHty  has  manifested  itself  in  the  discovery  of 
Maxwell,  who  has  shown  that  the  nature  of  hght  is  founded 
on  a  process  of  periodic  electromagnetic  disturbances.  Hence, 
so  concludes  Duhem,  experiment  can  never  decide  whether  a 
certain  theory  is  alone  valid.  The  physicist  is  never  certain 
that  he  has  exhausted  all  conceivable  possibilities  of  thought. 
The  truth  of  a  physical  statement,  the  vahdity  of  a  discovery, 
cannot  be  confirmed  by  any  experimentum  crucis. 

According  to  this  argument,  therefore,  it  is  also  possible 


THE  DISCOVERER  107 

that  the  scientific  grounds  of  spectral  analysis  do  not  conform 
to  truth.  A  contradictory  hypothesis  may,  indeed,  be  set 
up,  with  the  result  that  the  same  experiments  that  had  led 
Kirchhoff 's  discovery  from  one  triumph  to  another  would  have 
to  be  interpreted  in  a  totally  different  sense. 

I  must  frankly  confess  that  I  cannot  subscribe  to  such  an 
extreme  eventuahty,  since,  in  my  opinion,  Duhem's  analogy 
with  mathematics  excludes  this  possibiUty.  For  if  a  certain 
probability  is  expressed  by  a  trilUon  to  one,  then  I  venture  to 
state  that  even  in  the  case  of  mathematical  truths  certainty 
reaches  no  higher  degree  of  probabihty.  From  the  history  of 
mathematics  we  know  of  theorems  which  were  enunciated 
and  provided  with  complete  proofs,  and  yet  did  not  succeed 
in  estabhshing  themselves ;  hence  we  see  that,  however  evident 
a  mathematical  theorem  may  be,  it  is  still  only  a  matter  of 
very  great  probabihty. 

If,  following  our  usual  habits  of  thought,  we  take  this  for 
absolute  certainty,  then  we  may  also  consider  the  sum-total 
of  experiments  in  the  realm  of  spectral  analysis  to  be  a  great 
experimentum  crucis  for  the  correctness  of  the  theory  itself. 

Far  removed  from  it,  and  yet  connected  with  it,  there  is 
the  "  Periodic  System  of  the  Elements,"  the  discovery  of 
Mendelejew  and  Lothar  Meyer.  It,  too,  offered  prophetic 
glances  into  the  future,  foretold  the  unknown,  hinted  at  things 
that  were  present  only  in  imagination  in  a  scheme  of  thought 
that  assigned  definite  places  of  existence  to  undiscovered  things. 
The  Periodic  System  is  represented  by  a  table  containing 
vertical  and  horizontal  rows,  in  the  squares  of  which  the 
elements  are  entered  according  to  certain  rules  depending  on 
their  atomic  weights.  The  discovery  consisted  theoretically 
in  stating  that  the  physical  and  chemical  properties  of  each 
element  is  the  arithmetic  mean  between  the  properties  of  its 
horizontal  and  vertical  neighbours.  This  gave  rise  to  pre- 
dictions concerning  the  unoccupied  squares.  These  gaps, 
these  blank  spaces  in  the  table,  seem  to  say  prophetically : 
There  are  elements  missing  here  that  must  be  discoverable. 
The  neighbours  will  betray  them,  and  the  empty  space  itself 
shows  by  what  means  they  are  to  be  found.  With  the  shrewd- 
ness of  a  detective,  Mendelejew  was  able  to  say  :  There  must 
be  elements  of  the  atomic  weights  44,  70,  and  72  ;  we  do  not 


108  EINSTEIN  THE  SEARCHER 

know  them  yet,  but  we  are  in  a  position  to  determine  the 
properties  of  these  foundlings  of  the  future,  and,  what  is  more, 
the  properties  of  their  compounds  with  other  elements.  Later 
researches,  which  led  to  the  discovery  of  the  elements. 
Scandium,  Gallium,  and  Germanium,  liave  actually  confirmed 
all  these  predicted  properties. 

The  metal  GalUum  was  discovered  in  1875  by  spectroscopic 
means.  Its  properties  are  the  mean  of  those  of  Aluminium 
and  Indium,  and  this  places  it  in  a  position  which  had  already 
been  assigned  to  it  in  the  periodic  table  before  its  discovery ;  for, 
owing  to  a  gap  in  the  system,  Mendelejew  had  asserted  its 
existence  five  years  previously,  although  he  then  knew  nothing 
of  its  characteristic  spectral  signs,  namely,  two  beautiful  violet 
lines.  Radium,  too,  which  was  discovered  in  1900  and  was 
found  to  have  the  atomic  weight  226,  completely  satisfied  this 
test  and  fitted  exactly  into  the  place  which  this  number 
reserved  for  it  in  the  table.  Thus  prediction  and  confirmatory 
discovery  were  fully  congruent  in  this  case  ;  the  experiment 
followed  on  the  visionary  insight  just  as  a  EucHdean  proof 
follows  on  a  mathematical  assertion,  and  we  have  every  reason 
to  say  that  the  system  of  Mendelejew  and  Lothar  Meyer  has 
stood  the  crucial  test.  Future  hypotheses  will  perhaps  sup- 
plement the  system  or  enlarge  our  knowledge  of  it,  but  will 
certainly  not  reduce  it  ad  absurdum. 

Apart  from  these  cases,  there  are  achievements  by  men 
who  may  be  called  lucky  discoverers,  although  they  displayed 
no  genius  for  finding  nor  for  creating.  The  philosopher- 
physicist,  Ernst  Mach,  has  devoted  a  lecture  to  such  intellects, 
which  seems  to  me  very  valuable,  if  only  for  the  reason  that  he 
traces  back  the  conceptions  of  discovery  and  invention  to  one 
common  root  of  knowledge,  and  explains  their  difference  as 
being  due  only  to  a  difference  in  the  appHcation  of  this 
discovery. 

But  when  Ernst  Mach  in  this  lecture,  "  On  the  Influence 
of  Accidental  Circumstances  on  the  Development  of  Inventions 
and  Discoveries,*'  extends  the  influence  of  chance  to  include 
accidental  circumstances  that  can  only  enter  when  the  dis- 
coverer is  closely  attentive,  it  seems  to  me  that  certain  limita- 
tions are  advisable.     Otherwise,  if  we  pursue  Mach's  fine  of 


THE  DISCOVERER  109 

thought  to  its  extreme,  we  could  declare  every  discovery  to 
be  due  to  chance,  and  this  would  be  the  end  of  the  intuitive- 
creative  idea.  This  assertion  would  ultimately  mean  that 
genius  owes  its  achievements  to  the  accidental  arrangement 
of  the  molecules  in  the  brain-cells  of  its  associated  body.  This 
would  be  just  as  wrong  as  saying  that  chess  is  a  game  of  chance 
because  we  lose  a  game  when,  by  chance,  we  come  up  against  a 
better  player. 

Huyghens,  the  great  discoverer  and  inventor,  says,  in  his 
Dtoptrica,  that  he  would  have  to  consider  anyone  who  invented 
the  telescope  without  the  favourable  intervention  of  chance 
to  be  a  superhuman  genius.  Why  should  he  choose  just  the 
telescope  ?  To  many  the  invention  of  the  Differential  Calculus 
will  appear  grander  and  due  to  a  higher  degree  of  ingenuity. 
And  since  it  was  produced  quite  methodically,  and  since  chance 
was  excluded,  we  may  follow  Huyghens  and  with  good  reason 
proclcdm  its  authors  superhuman  geniuses. 

Many  a  true  inspiration  is  dependent  on  some  impulse  from 
without.  Who  discovered  Elect romagnetism  ?  The  world- 
echo  answers,  "  Oersted,"  with  the  same  confidence  that  it 
couples  together  the  names  America  smd  Columbus.  This 
shows  how  enormously  important  was  the  achievement. 
Next  to  steam-power  nothing  has  exerted  such  a  revolutionary 
influence  in  all  branches  as  electromagnetism.  Without  it, 
the  world  of  to-day  would  present  a  totally  different  aspect. 
Without  it,  we  should  have  no  dynamos,  no  electric  trams,  no 
telegraphy,  no  electric-power  stations,  all  of  which  are  due  to 
the  work  of  Arago,  Gay-Lussac,  Ampere,  Faraday,  Gramme, 
and  Siemens.  Without  it,  there  would  be  none  of  the  abundance 
of  brilHant  discoveries  that  are  associated  with  the  names  of 
Maxwell,  Hertz,  and  Einstein.  The  fact  that  physics  used  to  be 
divided  into  three  parts — Mechanics,  Optics,  Electrodynamics 
— and  that,  since  then,  the  coherent  unity  of  the  physical 
picture  of  the  world  has  been  developed,  shows  us  a  picture  in 
the  background  of  which  we  see  the  illuminating  figure  of  Hans 
Christian  Oersted.  It  must  not  be  overlooked,  however,  that 
in  the  case  of  his  great  discovery,  too,  chance  played  a  definite 
part.  It  occurred  one  day  when  Oersted  was  holding  a  lecture 
in  the  winter  of  1819-20  ;   a  magnetic  needle  situated  near 


110  EINSTEIN  THE  SEARCHER 

his  Volta-battery  began  to  vibrate  irregularly.  This  appar- 
ently unimportant  trembUng  of  the  metal  points  contained  the 
key  to  a  fact,  the  whole  consequences  of  which  could  in  no 
conceivable  way  have  entered  the  mind  of  this  observer  of  a 
hundred  years  ago,  in  spite  of  the  genius  of  the  Danish  scientist, 
which  is  documented  in  the  classical  and  far-famed  dissertation, 
*'  Experiment  a  circa  effectum  conflictus  electrici  in  Acum 
magneticam,"  which  appeared  in  July  1820.  It  cleared  the 
way  for  intuitions  that  were  equally  as  fruitful  for  theory  as  for 
practice.  Thirteen  years  after  this  initial  discovery  the  world 
saw  the  first  very  important  consequence  in  Gauss'  and  Weber's 
electric  telegraph,  and  a  Uttle  later  the  eminent  discoverer 
Fechner,  in  Leipzig,  proclaimed  it  as  his  conviction  that, 
within  two  years,  electromagnetism  would  entirely  reform  the 
world  of  machines,  and  would  entirely  supersede  steam-  and 
water-power.  Of  course,  his  time  estimate  fell  far  short  of  the 
mark.  It  has  been  reserved  for  the  present  generation  to 
reaHze  that  we  live  in  an  electromagnetic  world,  and  that  we 
have,  theoretically  and  practically,  to  spend  our  hfe  electro- 
magnetically.  The  first  indication  of  this  knowledge  hung 
upon  the  quivering  point  of  a  magnetic  needle,  and  from  it 
there  evolved  the  electromagnetic  ideas  that  we  are  so  fond  of 
picturing  as  our  handmaids,  but  which,  in  reality,  are  sovereign 
over  us  all. 

A  great  deal  of  the  history  of  discovery  must  be  revised 
and  corrected.  The  Spiral  of  Archimedes  is  not  due  to 
Archimedes,  nor  Marriotte's  Law  to  Marriotte,  nor  Cardan's 
formula  to  Cardan,  nor  Crookes'  Tube  to  Crookes,  and  Galvan- 
ism is  only  related  to  Galvani  by  the  following  anecdote.  It 
arose  from  an  accidental  experience  of  Madame  Galvani  in 
the  kitchen  :  a  half-skinned  frog  that  was  to  be  fried  for  the 
evening  meal  happened  to  rest  between  a  scalpel  and  a  tin  plate, 
which  brought  it  into  metalHc  contact  with  an  accidental 
discharge  of  electricity  ;  the  frog  twitched  ;  the  head  of  the 
house  gave  a  very  naive  interpretation  to  the  phenomenon  ; 
and  it  was  under  such  auspices  that  Galvanism  made  its  entry 
into  the  world.  It  would  be  a  futile  task  to  endeavour  to  trace 
the  connexion  between  experiment  and  the  underlying  idea, 
which,  in  this  case,  first  came  to  life  in  Alexander  Volta,    What 


THE  DISCOVERER  111 

would  have  remained  a  mere  frog-dance  if  left  to  Galvani  now 
acquired  the  rank  of  a  discovery  through  the  work  of  a  thinking 
physicist,  who  set  up  a  "  Voltaic  series  "  ;  this  discovery  then 
assumed  power  and  dignity  in  the  hands  of  Nicholson,  Davy, 
Thomson,  Helmholtz,  and  Nernst.  The  words  Galvanic  Elec- 
tricity should  be  made  to  give  way  entirely  to  Voltaic 
Electricity,*  as  in  the  case  of  many  another  expression  for 
which  chance  and  insufficient  thought  have  stood  sponsor. 

It  often  happens  that  experiment  acts  as  a  corrective  of 
the  underlpng  idea,  neither  confirming  nor  contradicting,  but 
nursing  it,  as  it  were,  strengthening,  and  purging  it  of  errors. 
Such  experiments,  partly  in  conjimction  with  chance,  play 
an  important,  sometimes  a  decisive,  role  in   the   works  of 
Dufay,  Bradley,  Foucault,  Fresnel,  Fraunhofer,  and  Rontgen. 
Faraday,   who   was  incapable   of   observing  otherwise   than 
intensively,  found  himself  compelled,  whilst  stud5dng  induction 
phenomena,  to  alter  his  initial  view,  and  it  is  just  this  correction 
by  experiment  that  constitutes  Faraday's  real  discovery.     In 
many  cases  the  initial  idea  is  corrected,  nay  surpassed,  by  te 
result.     Columbus  worked  methodically  when  he  set  out  to 
reach  the  East  Indies  by  travelling  westwards  ;   but  what  he 
discovered  was  not  a  confirmation  of  his  nautical  idea  only,  but 
something  much  greater,  which  certainly  did  not  He  in  his 
calculation.     Thus  he  became  the  archetype  of  all  searchers, 
who  had  thought  out  and  anticipated  essentially  different 
conditions  from  those  that  were  afterwards  discovered  to  be 
prevalent.     Among  these  are  to  be  counted  Priestley  and 
Cavendish,  who  clung  to  the  erroneous  notion  of  phlogiston, 
even  when  they  had  the  evidence  to  the  contrary  in  the  ele- 
ments they  had  themselves  discovered,  namely,  oxygen  and 
hydrogen.     Graham  Bell,  the  inventor,  was  seeking  something 
quite  different  from  what  he  later  hit  on  :  as  a  teacher  of  the 
deaf  and  dumb  he  was  trying  to  give  a  visual  picture  of  sounds, 
in  order  to  make  clear  the  formation  of  soimds  to  his  pupils  ; 
this  led  him  to  construct  an  electrical  apparatus,  which  finally 
led  to  the  discovery  of  the  telephone. 

The  truest  and  sharpest  contrast  with  the  experimentum 
cruets  is  furnished  by  experiment  when  it  shows  the  exact 

*  The  usual  term  in  England  is  Voltaic  Electricity,  or,  simply,  Current 
Electricity.— H.  L.  B. 


112  EINSTEIN  THE  SEARCHER 

opposite  of  what  the  explorer  was  expecting.  But  since  an 
absolute  No  entails  a  very  decisive  Yes — ^namely,  in  this  case, 
the  affirmation  of  a  relationship  that  was  previously  held  to 
be  impossible — a  negative  experiment  of  this  kind,  when  it 
occurs,  will  be  followed  by  momentous  consequences ;  these 
will  be  the  more  important  in  proportion  as  the  question,  the 
affirmation  of  which  was  expected  by  the  physicist,  is  of  a 
fundamental  character. 

The  experiments  of  Michelson  and  Morley,  directed  at 
proving  the  existence  of  the  ether,  are  to  be  regarded  as  the  true 
classical  instances  of  these  experiments  answering  with  an 
overwhelming  negative.  Their  first  effect  was  to  produce  a 
sense  of  helplessness,  a  check  to  thought,  a  void  in  the  chamber 
of  ideas.  And  to  fill  this  void  there  arose  new  views  of  the 
world  in  which  we  nowadays  recognize  the  true  thought - 
pictures  of  the  universe.  The  great  names — Lorentz,  Min- 
kowski, Albert  Einstein — shone  out  ! 

As  there  are  forerunners  for  almost  every  important  event, 
so  also  in  the  case  of  the  experimentum  cruets  of  Michelson 
and  Morley.  Henri  Poincar^,  the  famous  mathematician, 
whilst  still  a  student  of  the  ficole  Polytechnique,  had  initiated 
experiments  with  his  fellow-student  Fav6,  which  followed 
the  same  object.  The  Michelson-Morley  experiment  was  at 
least  a  hundred  times  more  accurate.  In  each  case  the  con- 
clusion was  that  the  laws  of  optics  are  not  disturbed  by  a 
motion  of  translation,  such  as  that  of  the  earth  through  space 
this  is,  however,  contrary  to  what  the  old  physical  ideas  lead 
us  to  expect. 

If  we  assume  the  existence  of  a  space-filling  ether,  the 
earth,  owing  to  its  own  velocity  of  nineteen  miles  per  second, 
would  have  to  pass  through  a  hurricane  just  as  in  the  case  of 
travellers  sitting  in  an  open  train  rushing  along  at  very  great 
speed.  If  we  send  out  Hght  rays  in  all  directions  simultane- 
ously from  any  point  on  the  earth's  surface,  some  will  travel 
in  the  teeth  of  the  ether-storm,  others  will  experience  only  a 
part  of  the  storm's  power ;  so  that  of  two  hght -rays  travelling 
in  exactly  opposite  directions  the  retardation  of  the  one  should 
be  equal  to  the  acceleration  of  the  other  ;  and  yet  they  are  not 
quite  equal,  for  a  simple  calculation  shows  that  in  every  case 
the  retardation  is  slightly  more  than  the  acceleration. 


THE  DISCOVERER  118 

This  may  be  made  clear  by  means  of  a  model  of  easy  con- 
struction, or,  better  still,  by  considering  a  ship  that  is  subject 
to  a  constant  current  and,  simultaneously,  to  a  pressure  of  the 
wind.  The  time  taken  by  the  boat  in  making  a  trip  up  and 
down  stream  can  never  be  the  same  for  the  cases  when  the 
wind  is  in  the  direction  of  the  current,  and  vice  versa. 

In  the  case  of  the  ray  of  light,  which  is  sent  backwards  and 
forwards  by  means  of  a  contrivance  of  mirrors,  this  fact  should 
be  clearly  demonstrated  by  means  of  the  interference-fringes, 
which  are  able  to  show  much  smaller  effects  than  the  experi- 
ment demands.  The  experimental  oracle  was  to  speak,  but 
it  remained  silent.  This  portentous  silence  signified  :  no 
interference-effect,  no  action  of  the  ether-current,  no  influence 
due  to  translation — ^nothing  ! 

This  "  nothing  "  compelled  a  decision  of  a  very  startling 
kind,  for  the  result  of  this  experiment  was  in  direct  contradic- 
tion to  another  famous  experiment.  Fizeau  had  proved  that 
the  ether  is  practically  rigid  and  remains  fixed  in  interstellar 
space.  A  decision  had  to  be  taken  in  favour  of  Fizeau  or 
Michelson  and  Morley.  Yet  this  was  impossible,  for  both  had 
operated  with  unsurpassable  accuracy.  It  was  impossible 
to  reconcile  both  views  as  they  were  diametrically  opposed. 
This  contradiction  remains,  even  if  we  assume  a  different 
hypothesis,  not  involving  the  ether,  for  Fizeau's  experiment. 
A  solution  was  impossible  without  undertaking  revolutionary 
changes  in  the  whole  of  physical  thought. 

This  radical  change  was  effected  by  Einstein ;  and  this 
mysterious  contradiction  disappeared  in  the  resulting  revolu- 
tion of  thought.  Einstein  supplanted  the  absolute  time- 
conception  by  a  new  relative  conception,  and  thus  the  perplex- 
ing problem  disappeared.  Two  great  principles  arose  as 
regulative  factors  in  thought,  and  wherever  these  were  apphed, 
they  achieved  wonders  :  one  was  the  new  conception  of  time 
that  deprived  the  earth  of  her  unique  position  as  the  sovereign 
of  time  by  the  introduction  of  the  principle  that  the  rate  at 
which  time  elapses  is  different  in  media  moving  at  different 
speeds  ;  the  other  is  the  principle  of  the  constancy  of  the 
velocity  of  light.  One  feels  a  temptation  to  apply  a  mythical 
allegory :  just  as  the  world,  according  to  the  Biblical  story, 
originated  from  nothing,  so  there  arose  from  the  "  nothing  " 
8 


114  EINSTEIN  THE  SEARCHER 

of  the  Michelson-Morley  experiment  a  new  world,  a  world  of 
knowledge,  a  cosmos  of  thought,  in  which  perfect  harmony 
reigns. 

Its  truth  was  contained  in  itself  before  the  experimental 
proof  was  furnished.  And  this  reaUzation  of  truth  has  become 
a  fact  in  the  experimentum  cruets  for  which  the  sun  and  stars 
formed  the  material.  This  will  be  discussed  in  another  part 
of  the  book. 

"  The  really  important  factor  is  ultimately  intuition," 
Einstein  had  said  to  me.  It  made  me  think  of  Huyghens' 
remark  about  the  genius  who  would  have  been  able  to  create 
the  telescope  without  the  help  of  chance.  Was  not  this  in- 
tellect, imagined  by  Huyghens,  sitting  opposite  me  at  that 
moment  ?  An  inner  voice  answered  in  the  affirmative,  for 
Einstein's  thought -complex  seemed  to  me  at  that  moment  a 
kind  of  telescope  for  the  human  mind,  a  telescope  that  had 
arisen  out  of  pure  intuition,  and  whose  range  stretched  to  the 
limits  of  the  universe 


CHAPTER  VI 
OF  DIFFERENT  WORLDS 

Imaginary  Experiment  with  *'  Lumen." — Impossibilities. — A  Destroyed 
Illusion. — Is  the  World  Infinite  ? — Surface  Creatures  and  Shadow  Rambles. 
— What  is  the  Beyond  ? — Action  at  a  Distance. — Ideas  of  Multi-dimensional 
Regions. — Hypnotism. — Recollections  of  Zollner. — Science  and  Dogma. — The 
Trial  of  Galilei. 

A  CONVERSATION  held  during  April  1920  destroyed 
an  illusion  which  had  become  dear  to  me. 
It  concerned  the  fantastic  figure,  **  Lumen/'  con- 
ceived as  an  actual  human  being,  imagined  as  endowed  with 
an  extraordinary  power  of  motion  and  keenness  of  sight.  Mr. 
Lumen  is  supposed  to  be  the  invention  of  the  astronomer 
Flammarion,  who  produced  him  in  the  retort  of  fancy,  as  Faust 
produced  Homunculus,  to  use  him  to  prove  the  possibihty  of 
very  remarkable  happenings,  in  particular,  the  reversal  of 
Time. 

Einstein  declared  outright  :  "  Firstly,  Lumen  is  not  due 
to  Flammarion,  who  has  derived  him  from  other  sources  ;  and 
secondly,  Lumen  can  in  no  way  be  used  as  a  means  of  proving 
things." 

MoszKOWSKi :  **  It  is  at  least  very  interesting  to  operate 
with  him.  Lumen  is  supposed  to  have  a  velocity  greater  than 
that  of  light.  Let  us  assume  this  as  given,  then  the  rest  follows 
quite  logically.     If,  for  example,  he  leaves  the  earth  on  the  day 

of  a  great  event,  such  as  the  battle  of  Waterloo,  and May 

I  trace  out  this  example,  at  the  risk  of  tiring  you  ?  " 

Einstein  :  Do  repeat  it,  and  act  as  if  you  were  telling  some- 
thing entirely  new.  It  is  clear  that  the  Lumen-story  gives 
you  great  amusement,  so  please  talk  quite  freely.  But  I  can- 
not forgo  the  privilege  of  showing  later  how  the  whole  adven- 
ture and  its  consequences  must  be  demolished. 

M.  :  Well  then,  the  person.  Lumen,  sets  off  at  the  end  of 
the  battle  of  Waterloo  to  make  an  excursion  into  space  with  a 

115 


116  EINSTEIN  THE  SEARCHER 

speed  of  250,000  miles  per  second.  He  thus  catches  up  all  the 
light -rays  that  left  the  field  of  battle  and  moved  in  his  direction. 
After  an  hour  he  will  already  have  attained  a  lead  of  about 
twenty  minutes.  This  lead  will  be  gradually  increased,  so  that 
at  the  end  of  the  second  day  he  will  no  longer  be  seeing  the 
end  of  the  battle,  but  the  beginning.  What  has  Lumen  been 
seeing  in  the  meantime  ?  Clearly  he  has  been  observing  events 
happening  in  the  reverse  direction,  as  in  the  case  of  a  cinemato- 
graph which  is  exhibiting  pictures  backwards.  He  saw  the  pro- 
jectiles leaving  the  objects  they  had  struck,  and  returning  into 
the  mouths  of  the  cannon.  He  saw  the  dead  come  to  Hfe,  arise, 
and  arrange  themselves  into  battahon  order.  He  would  thus 
arrive  at  an  exactly  opposite  view  of  the  passing  of  time,  for 
what  he  observes  is  as  much  his  experience  as  what  we  observe 
is  ours.  If  he  had  seen  all  the  battles  of  history  and,  in  fact, 
all  events  happening  in  the  reverse  order,  then  in  his  mind 
"  before  "  and  "  after  "  would  be  interchanged.  That  is,  he 
would  experience  time  backwards ;  what  are  causes  to  us 
would  be  effects  to  him,  and  our  effects  would  be  his  causes  ; 
antecedents  and  consequents  would  change  places,  and  he 
would  arrive  at  a  causality  diametrically  opposite  to  our 
own.  He  would  be  quite  as  justified  in  adopting  his  view  of 
the  happening  of  things,  according  to  his  experiences,  and  of 
the  causal  nexus  as  it  appears  to  him,  as  we  are  justified  in 
adopting  ours. 

Einstein  :  And  the  whole  story  is  mere  humbug,  absurd, 
and  based  on  false  premises,  leading  to  entirely  false  con- 
clusions. 

M.  :  But  it  is  only  to  be  taken  as  an  imaginary  experiment 
that  plays  with  fantastic  impossibilities  to  direct  our  ideas  on 
to  the  relativity  of  time  by  a  striking  illustration.  Did  not 
Henri  Poincar6  adduce  this  extreme  example  to  discuss  the 
"  reversal  "  of  time  ? 

Einstein  :  You  may  rest  assured  that  Poincar^,  even  if  he 
used  this  example  as  an  entertaining  digression  in  his  lectures, 
took  the  same  view  of  Lumen  as  I  do.  It  is  not  an  imaginary 
experiment  :  it  is  a  farce,  or,  to  express  it  more  bluntly,  it  is 
a  mere  swindle !  These  experiences  and  topsy-turvy  per- 
ceptions have  just  as  little  to  do  with  the  relativity  of  time, 
such  as  it  is  taught  by  the  new  machanics,  as  have  the  personal 


OF  DIFFERENT  WORLDS  117 

sensations  of  a  man,  to  whom  time  seems  long  or  short  accord- 
ing as  he  experiences  pain  or  pleasure,  amusement  or  boredom. 
For,  in  this  case,  at  least  the  subjective  sensation  is  a  reahty, 
whereas  Lumen  cannot  have  reality  because  his  existence  is 
based  on  nonsense.  Lumen  is  to  have  a  speed  greater  than 
that  of  light.  This  is  not  only  an  impossible,  but  a  fooHsh 
assumption,  because  the  theory  of  relativity  has  shown  that 
the  velocity  of  Ught  cannot  be  exceeded.  However  great  the 
accelerating  force  may  be,  and  for  however  long  it  may  act,  it 
cannot  cause  this  Hmit  to  be  transcended.  Lumen  is  supposed 
to  be  equipped  with  the  organ  of  sight,  that  is,  he  is  supposed 
to  have  a  corporal  existence.  But  the  mass  of  a  body  be- 
comes infinitely  great  when  it  reaches  the  velocity  of  hght,  so 
that  it  is  quite  absurd  to  go  beyond  this  stage.  It  is  admissible 
to  operate  with  impossibiUties  in  imagination,  that  is,  with 
things  that  contradict  our  practical  experience,  but  not  with 
absolute  nonsense.  That  is  why  the  other  adventure  of  Lumen, 
in  which  he  jumps  to  the  moon,  is  also  an  absurdity.  In  this, 
he  is  supposed  to  leap  with  a  speed  greater  than  Ught,  and, 
when  he  reaches  the  moon,  to  turn  round  instantaneously, 
with  the  result  that  he  sees  himself  jumping  from  the  moon  to 
the  earth  backwards !  This  jump  is  logically  meaningless ; 
and  if  we  try  to  make  deductions  of  an  optical  nature  from 
such  a  nonsensical  assumption,  we  deceive  ourselves. 

M. :  Nevertheless,  I  should  claim  extenuating  circum- 
stances for  this  case  on  the  ground  that  I  am  enUsting  the 
help  of  the  conception  of  impossibiUty.  A  journey  even  at 
a  speed  of  only  looo  miles  per  second  is  impossible  for  a  man 
or  a  homuncT^lus. 

Einstein  :  Yes,  according  to  our  experience,  if  we  measure 
it  against  facts.  We  cannot  state  definitely  that  a  journey 
into  the  imiverse  at  an  enormous  yet  Hmited  velocity  is  abso- 
lutely impossible.  Within  the  indicated  bounds  every  play  of 
thought  that  is  argued  correctly  is  allowable. 

M. :  Now,  suppose  that  I  strip  Lumen  of  all  bodily  organs 
and  take  him  as  being  a  pure  creature  of  thought,  entirely 
without  substance.  A  velocity  greater  than  that  of  light 
can  be  imagined,  even  if  it  cannot  be  reahzed  physically.  If, 
for  example,  we  think  of  a  Ught  house  with  a  revolving  Ught, 
and  consider  a  beam  of  Ught  about  600  miles  long,  which  rotates 


118  EINSTEIN  THE  SEARCHER 

200  times  per  second.  Then  we  could  represent  to  ourselves 
that  the  light  at  the  circumference  of  this  beam  travels  with  a 
speed  of  nearly  760,000  miles  per  second. 

Einstein  :  As  for  that,  I  can  give  you  a  much  better  ex- 
ample of  the  same  thing.  We  need  only  imagine  that  the 
earth  is  poised  in  space,  motionless,  and  non-rotating.  This 
is  physically  admissible.  Then  the  most  distant  stars,  as 
judged  by  us,  would  describe  their  paths  with  almost  un- 
limited velocities.  But  this  projects  us  right  out  of  the 
world  of  reahty  into  a  pure  fiction  of  thought,  which,  if 
followed  to  its  conclusion,  leads  to  the  most  degenerate  form 
of  imagination,  namely,  to  pathological  individuahsm.  It  is 
in  these  realms  of  thought  that  such  perversities  as  the 
reversal  of  time  and  causality  occur. 

M. :  Dreams,  too,  are  confined  to  the  individual.  Reality 
constrains  all  human  beings  to  exist  in  one  and  the  same  world, 
whereas,  in  dreams,  each  one  has  his  own  world  with  a  different 
kind  of  causahty.  Nevertheless,  dreams  are  a  positive  experi- 
ence, and  signify  a  reahty  for  the  dreamer.  Even  for  waking 
reality  it  would  be  easy  to  construct  cases  in  which  the  causal  re- 
lationship is  shattered.  Suppose  a  person  who  has  grown  up  in 
a  confined  retreat,  such  as  Kaspar  Hauser,  looks  in  a  mirror  for 
the  first  time  in  his  life.  As  he  knows  nothing  of  the  pheno- 
mena of  optical  reflexion,  he  sees  in  it  a  new,  objective  world 
that  gives  a  shock  to,  or  even  subverts,  his  own  idea  of  causality 
in  so  far  as  it  may  have  become  developed  in  him.  Lumen  sees 
himself  jump  backwards,  whereas  Kaspar  Hauser  sees  himself 
performing  gestures  on  the  wrong  side  of  his  body ;  should  it 
not  be  possible  to  draw  a  reasonable  parallel  between  these  two 
cases  ? 

Einstein  :  Quite  impossible.  However  you  set  about  it, 
your  Lumen  will  inevitably  come  to  grief  on  the  conception  of 
time.  Time,  denoted  in  physical  expressions  by  the  symbol 
"  t,"  may,  indeed,  be  given  a  negative  value  in  these  equations, 
so  that  an  event  may  be  calculated  in  the  reverse  direction. 
^  But  then  we  are  dealing  with  pure  matters  of  calculation,  and 
in  this  case  we  must  not  allow  ourselves  to  be  drawn  into 
the  erroneous  belief  that  time  itself  may  travel  negatively, 
that  is,  retrogressively.  This  is  the  root  of  the  misapprehension : 
that  what  is  allowable  and  indeed  necessary  in  calculations 


OF  DIFFERENT  WORLDS  119 

is  confused  with  what  may  be  thought  possible  in  Reality.* 
Whoever  seeks  to  derive  new  knowledge  from  the  excursions 
of  a  creature  Uke  Lumen  into  space,  confuses  the  time  of  an 
experience  with  the  time  of  the  objective  event ;  but  the 
former  can  have  a  definite  meaning  only  if  it  is  founded  on 
a  proper  causal  relation  of  space  and  time.  In  the  above 
imaginary  experiment  the  order  of  the  experiences  in  time  is 
the  reverse  of  that  of  the  events.  And  as  far  as  causality  is 
concerned,  it  is  a  scientific  conception  that  relates  only  to 
events  ordered  in  space  and  time,  and  not  to  experiences.  In 
brief,  the  experiments  with  Lumen  are  swindles. 

M.  :  I  must  resign  myself  to  giving  up  these  illusions.  I 
must  frankly  confess  that  I  do  so  with  a  certain  sadness,  for 
such  bold  flights  of  constructive  fancy  exert  a  powerful  attrac- 
tion on  me.  At  one  time  I  was  near  outdoing  Lumen  by 
assuming  a  Super-Lumen,  who  was  to  traverse  aU  worlds  at 
once  with  infinite  velocity.  He  would  then  be  in  a  position  to 
take  a  survey  of  the  whole  of  universal  history  at  a  single 
glance.  From  the  nearest  star,  Alpha  Centauri,  he  would 
see  the  earth  as  it  was  four  years  ago  ;  from  the  Pole  Star,  as 
it  was  forty  years  ago ;  and  from  the  boundary  of  the  Milky 
Way,  as  it  was  four  thousand  years  ago.  At  the  same  moment 
he  could  choose  a  point  of  observation  that  would  enable  him 
to  see  the  First  Crusade,  the  Siege  of  Troy,  the  Flood,  and 
also  the  events  of  the  present  day  simultaneously. 

Einstein  :  And  this  flight  of  thought,  which,  by  the  way, 
has  been  indulged  in  repeatedly  by  others  too,  has  much  more 
sense  in  it  than  the  former  one,  because  you  may  make  an 
abstraction  which  disregards  speed  cdtogether.  It  is  only  a 
limiting  case  of  reflection. 

M.  :  I  should  Hke  to  touch  on  other  Hmiting  cases,  in 
particular  two  that  I  find  it  impossible  to  interpret.  Lotze 
mentions  them  in  his  Logic.  The  first  concerns  the  infinitely 
long  lever  whose  fulcrum,  or  turning-point,  is  at  the  confines 
of  the  universe.     According  to  the  Laws  of  Levers,  a  mass  of 

*  Perhaps  an  analogy  will  serve  to  make  this  clear.  Suppose  that  a  certain 
quantity  of  some  foodstuff  is  consumed  by  ^(^  head  of  population.  The 
false  inference  would  be  that  a  population  is  possible  which  has  ^  heads ! 
In  the  same  way  the  statistics  may  be  quite  correct  in  arriving  at  the  figure  | 
suicides,  but  if  we  leave  the  realms  of  calculation,  then  the  ^  suicide  loses  its 
meaning  entirely. 


120  EINSTEIN  THE  SEARCHER 

magnitude  zero  will  suffice  to  keep  in  equilibrium  at  the  end 
of  the  other  lever-arm  any  weight,  no  matter  whether  it  is 
a  million  times  heavier  than  the  earth.  Our  imaginations 
cannot  even  picture  this.  Yet  I  cannot  feel  satisfied  with  the 
mere  explanation  that  it  is  an  exceptional  case,  an  extension 
of  a  general  law  to  a  case  in  which  it  is  no  longer  appUcable. 
The  second  example  is  still  more  perplexing  because  it  does 
not  require  a  journey  into  other  worlds,  but  leads  us  into  in- 
conceivable consequences  even  if  we  remain  on  the  earth. 
Lotze  considers  this  second  limiting  case  easier ;  to  me  it 
seems  more  difi&cult.  It  is  this  :  The  force  that  a  wedge  exerts 
is  inversely  proportional  to  its  thickness.  If  it  is  infinitely 
thin,  this  formula  gives  an  infinitely  great  result,  whereas, 
actually,  the  force  exerted  is  nil.  This  very  thin  wedge,  trans- 
formed finally  into  a  geometrical  plane,  should  be  able  to  split 
in  twain  any  wooden  or  even  steel  block.  And  now,  consider 
a  special  arrangement  of  this  wedge  in  which  it  is  resting  with 
its  extremely  sharp  edge  vertically  downwards,  whereas  at  the 
top  it  broadens  to  a  Httle  ledge  which  supports  a  weight.  We 
then  get  the  incredible  result  that  this  wedge,  which  can  be 
imagined  concretely,  should  be  able  to  cut  through  the  whole 
earth  with  its  extremely  fine  edge,  if  placed  on  some  base. 
Where  is  the  fallacy  in  this  case  ? 

Einstein  :  The  mechanical  facts  have  not  been  taken 
suJB&ciently  into  consideration. — He  illustrated  his  further 
remarks  by  drawing  a  few  strokes  with  his  pen,  and  proved 
from  his  diagram  that  a  wedge  of  this  sort  would  be  able  to 
perform  what  I  assumed,  only  if  the  base  on  which  it  is  placed 
is  composed  of  separate  laminae.  Otherwise  the  assumption 
that  the  force  is  infinitely  great  would  be  erroneous. 

After  this  digression  to  a  limiting  case  on  the  earth  we 
returned  to  more  general  problems,  and  the  question  of  the 
finitude  or  infinitude  of  the  universe.  Shortly  before,  Einstein 
had  given  an  address  to  the  BerHn  Academy  on  this  point, 
involving  difficult  calculations,  and  I  hoped  to  hear  from  him 
an  easy  explanation  at  least  in  general  terms. 

It  is  one  of  the  ultimate  problems.  Whoever  talks  of  the 
limits  of  the  world  endeavours  also  to  mark  off  the  bounds 
of  the  understanding.    The  average  person,  at  first  sight, 


OF  DIFFERENT  WORLDS  121 

almost  always  decides  in  favour  of  an  infinite  universe,  on  the 
ground  that  a  finite  world  is  inconceivable.  He  argues  that,  if 
it  were  considered  finite,  we  should  immediately  be  confronted 
with  the  question  :  What  lies  beyond  the  finite  boundary  ? 
Something  must  be  present,  even  if  it  is  only  empty  space. 
This  brings  us  into  an  inevitable  conflict  with  the  first  of  Kant's 
*'  antinomies,"  with  the  thesis  and  antithesis,  from  which  there 
is  no  escape.  What  is  the  meaning  of  the  fact  that  the  appre- 
hensive understanding  seeks  refuge  in  **  Infinity  "  ?  It  signifies 
that  he  gets  entangled  in  the  folds  of  a  negative  conception, 
that  furnishes  him  with  no  explanation  at  all,  and  expresses 
merely  that  his  first  assumption  of  finitude  cannot  be  thought 
out  to  its  conclusion. 

Besides  this,  a  second  disturbing  question  arises.  Is  there 
a  finite  or  infinite  number  of  stellar  bodies  ?  If  this  question 
refers  to  an  assumed  infinite  space,  even  if  such  space  is  in- 
conceivable, then  there  are  two  possible  answers.  For  it 
would  be  possible  to  imagine  a  finite  number  of  stars  even  if 
'  no  hmit  could  be  found  for  space. 

Whereas  the  general  question  of  space  in  the  universe 
belongs  exclusively  to  speculative  philosophy,  the  star>question 
is  not  purely  metaphysical,  but  is  physical,  too,  and  has  accord- 
ingly been  treated  by  physicists.  The  great  astronomer 
Herschel  imagined  he  could  solve  it  by  means  of  optical  prin- 
.ciples,  and  he  arrived  at  the  conclusion  that  the  number  of 
heavenly  bodies  must  be  finite,  as  otherwise  the  aspect  of 
the  starry  firmament,  from  the  point  of  view  of  illumination, 
would  be  entirely  different.  But  this  proof  did  not  estabUsh 
itself  among  scientists,  for  the  number  of  stars  of  the  type  of 
the  sun  might  be  finite,  whilst  there  was  an  infinite  number 
of  dark  stars. 

A  further  question  presented  itself :  Would  it  be  possible 
for  a  definite  part  of  the  heavens  (say,  that  north  of  the  ecUptic) 
to  contain  an  infinite  number  of  stars,  whilst  other  parts  con- 
tained only  a  finite  number  ?  At  first  this  sounds  very  extra- 
ordinary, but  it  is  by  no  means  unreasonable,  as  a  concrete 
example  will  show  :  If,  on  a  scale  of  temperature,  we  count  the 
degrees  of  heat  from  a  certain  point,  then  they  stretch  ap- 
parently to  infinity  in  one  direction,  whereas  they  extend 
only  to  —  273°  (Centigrade)  in  the  other  direction,  that  is,  to  the 


122  EINSTEIN  THE  SEARCHER 

absolute  zero.  Thus  we  can  imagine  an  arrangement  which 
stretches  to  infinity  only  in  one  direction. 

To  get  an  insight  into  the  discussion  by  Einstein  which  is 
about  to  follow,  we  must  first  dispose  of  a  certain  arbitrariness 
of  language,  lying  in  the  customary  indiscriminate  use  of  the 
terms,  infinite,  immeasurable,  and  unbounded.  Suppose  we 
have  a  globe  about  one  foot  in  diameter,  the  surface  of  which 
is  inhabited  by  extremely  small,  ultramicroscopic  creatures 
that  can  move  about  freely  and  can  think.  The  surface  of  the 
sphere  constitutes  the  world  of  the  micro-men,  and  he  has  a 
very  good  reason  for  considering  it  infinite,  for,  however  far 
and  in  whatever  direction  he  may  move,  he  never  encounters 
a  boundary.  But  we,  who  live  in  our  space,  look  on  to  this 
spherical  surface,  and  recognize  that  his  judgment  is  erroneous. 
To  us  his  spherical  world  seems  decidedly  finite  and  quite 
measurable,  although  it  has  no  determinable  beginning  and  no 
end,  and  thus  must  appear  unbounded  to  the  micro-man.  In 
fact,  we  ourselves  may  regard  it  as  boundless,  if  we  can  succeed 
in  forming  an  abstraction  that  leaves  out  of  account  its  limita- 
tions in  our  own  space. 

Now,  it  might  occur  to  a  particularly  inteUigent  micro- 
being  to  undertake  a  voyage  for  the  purpose  of  making  measure- 
ments. He  carefully  marks  his  point  of  departure,  walks 
straight  ahead  in  a  certain  direction,  describing  a  circle  on  his 
sphere — a  circle  which  he  will  necessarily  regard  as  a  straight 
line.  He  continues  ever  onwards  in  the  firm  conviction  that 
he  is  getting  farther  and  farther  away  from  his  starting-point. 
Suddenly,  he  discovers  that  he  has  reached  it  again.  He  dis- 
covers, by  the  mark  he  made,  that  he  has  not  been  describing 
a  straight  line,  but  a  line  that  merges  into  itself. 

The  micro-professor  would  be  compelled  to  declare  :  Our 
world,  the  only  one  known  to  me,  is  not  infinite,  although  in  a 
certain  sense  boundless.  Moreover,  it  is  not  immeasurable, 
since  it  can  be  measured  in  at  least  one  direction  by  the  number 
of  steps  I  have  walked.  From  this  we  may  infer  that  our  former 
geometrical  view  was  either  wrong  or  incomplete,  and  that,  in 
order  to  understand  our  world  properly,  we  must  build  up  a 
new  geometry. 

We  may  assume  that  the  majority  of  the  remaining  micro- 
inhabitants  would  at  first  protest  strongly  against  this  decision. 


OF  DIFFERENT  WORLDS  128 

The  idea  that  a  hne,  which  appears  to  them  to  be  pointing 
always  in  the  same  direction,  is  curved,  seems  to  them  in- 
conceivable and  absurd.  They  would  only  gradually  overcome 
their  scruples  of  thought  by  getting  an  insight  into  a  newly 
developed  geometry  that  makes  clear  to  them  for  the  first  time 
the  conception  of  a  sphere. 

In  our  world  of  space,  which  includes  all  stars,  we  are  the 
micro-inhabitants.  We  have  been  bom  with,  or  have  in- 
herited, the  idea  of  a  straight  and  ever-advancing  path  in 
space,  and  we  become  filled  with  the  utmost  astonishment  if 
some  one  asks  us  to  beheve  that  if  we  undertake  a  voyage  in 
one  direction  out  into  the  universe,  beyond  Sirius  and  a  million 
times  farther,  we  should  finally  arrive  at  our  starting-point 
again,  although  we  had  not  changed  our  direction.  But  the 
macro-being,  who  belongs  to  a  universe  of  higher  dimensions 
and  who  looks  on  our  world  as  we  looked  on  the  above  spherical 
world  one  foot  in  diameter,  sees  the  narrowness  of  our  view. 
We,  too,  are  in  a  position  to  rise  above  this  narrow  view  by 
means  of  a  theory  founded  on  our  experience,  which  will  lead 
us  to  an  extended  world-geometry,  just  as  the  micro-professor 
used  his  experience  to  extend  his  theory  of  the  circle  to  include 
the  conception  of  a  sphere. 

After  these  preliminary  remarks  we  shall  endeavour  to  get 
an  insight  into  Einstein's  reasoning,  not  in  the  form  in  which 
it  was  originally  presented  (in  the  Report  of  the  Proceedings  of 
the  Berhn  Academy  of  Science  of  8th  February  1917),  but  in  a 
very  easy  description  which  was  given  to  me  during  a  conversa- 
tion. Here,  too,  I  shall  try  to  preserve  the  sense  of  Einstein's 
remarks  without  binding  myself  strictly  to  his  words.  For 
although  I  am  indebted  to  him  for  his  efforts  to  avoid  difi&cult 
points,  yet  the  aim  of  this  book  is,  if  possible,  to  make  the 
explanation  still  easier.  Any  lack  of  accuracy  arising  from 
this  last  simpUfication  is  to  be  debited  to  me.  The  new  form 
of  representing  the  argument,  which  is  as  important  as  it  is 
fascinating,  is,  of  course,  due  to  Einstein. 

The  final  result  stated  by  Einstein  was  :  The  universe,  both 
as  regards  extent  and  mass,  has  finite  limits  and  can  be 
measured.  If  anyone  asks  whether  this  can  be  pictured,  I  shaD 
not  deprive  him  of  the  hope.  All  that  is  required  is  a  power 
of  imagination  that  is  great  enough  to  follow  a  pictorial  de- 


124  EINSTEIN  THE  SEARCHER 

scription  and  that  can  take  up  the  right  attitude  towards  a  sort 
of  figurative  representation. 

Let  us  again  imagine  a  sphere  of  modest  dimensions  with 
its  two-dimensional  surface.  We  are  concerned  only  with 
the  latter,  and  not  with  the  cubical  content.  The  sphere  is  to 
be  considered  as  resting  on  an  absolutely  plane  white  table  of 
unlimited  extent  in  all  directions.  The  sphere  touches  the 
table  at  a  single  point  which  we  shall  call  its  South  Pole  ; 
on  the  top  side  directly  opposite,  we  have  the  North  Pole. 
To  simplify  matters  we  may  make  a  sketch  on  paper  of  a 
vertical  section  through  the  centre  of  the  sphere.  This  profile- 
picture  will  show  us  the  sphere  as  a  circle,  and  the  white 
table  as  a  straight  line  ;  the  line  joining  the  two  poles  is  the 
axis  of  the  globe,  and  the  sectional  circle  is  a  meridian. 

Let  us  further  suppose  a  creature  (resembhng,  say,  a  lady- 
bird in  shape)  having  length  and  breadth,  but  no  thickness,  to 
crawl  along  this  meridian.  Although  it  has  no  thickness,  we 
shall  imagine  it  to  have  one  property  of  a  solid  body,  that  of 
being  opaque,  so  that  it  can  throw  a  shadow  if  properly  illu- 
minated. We  assume  the  globe  itself  to  be  transparent. 
At  the  North  Pole  we  suppose  a  very  strong  point-source  of 
light,  a  little  electric  lamp,  that  sends  out  rays  freely  in  all 
directions. 

The  insect  begins  its  journey  at  the  South  Pole  and  sets 
out  along  the  meridian  to  reach  the  North  Pole.  It  is  illu- 
minated by  the  lamp  all  the  way,  so  that  it  continually  throws 
a  shadow  on  the  white  table.  The  shadow  moves  along  the 
table  farther  and  farther  from  the  South  Pole,  in  proportion 
as  the  insect  moves  up  the  meridian,  with  the  difference  that 
while  the  insect  is  describing  an  arc  of  a  circle,  its  shadow 
moves  along  a  straight  line.  The  position  of  the  shadow  can 
be  determined  at  any  moment  by  drawing  the  straight  line 
connecting  the  lamp  to  the  insect,  and  producing  it  to  meet 
the  white  surface  of  the  table  ;  the  point  of  intersection  is  the 
projection  of  the  insect  on  the  plane. 

At  the  beginning  of  the  excursion  the  shadow  is  exactly  as 
large  as  the  flat  insect  itself,  if  we  assume  that  its  dimensions 
are  negligible  compared  with  the  surface  of  the  sphere,  for 
it  will  then  coincide  with  its  own  shadow.  But  when  the  insect 
crawls  upwards,  its  shadow  will   increase,    because   of   the 


OF  DIFFERENT  WORLDS  125 

shortened  distance  between  the  insect  and  the  lamp,  and  because 
the  points  of  projection  on  the  table  separate  more  and  more 
as  their  distances  from  their  corresponding  points  on  the  sphere 
become  greater.  There  is  thus  a  twofold  increase.  The 
shadows  move  away  more  and  more  rapidly,  and  at  the  same 
time  increase  in  size. 

When  the  insect  gets  very  near  the  North  Pole,  its  shadow, 
now  of  enormous  dimensions,  has  moved  to  a  very  great  dis- 
tance ;  and  when  finally  it  reaches  the  Pole,  its  shadow 
becomes  infinitely  great  and  thus  stretches  to  infinity. 

But  let  the  insect  wander  on  along  the  meridian,  past  the 
North  Pole,  down  towards  the  South.  At  the  moment  when  it 
passes  the  upper  Pole  its  shadow  jumps  from  the  right  side  to 
the  left.  Its  shadow  now  emerges  from  an  infinite  distance  to 
the  left,  and,  instead  of  being  infinite  size,  again  becomes  finite 
in  dimensions  as  it  approaches.  It  contracts  as  it  approaches, 
and,  in  short,  the  same  process  as  occurred  during  the  first 
half  of  the  journey  now  occurs  in  the  reverse  order. 

[If  we  fix  on  the  critical  moment  of  the  jump  from  the  right 
to  the  left,  that  is,  from  plus  infinity  to  minus  infinity,  we  may 
encounter  difiiculties.  For  the  surface-creature  pursues  its 
way  without  interruption  and  continuously,  and  we  experience 
a  wish  to  ascribe  to  it  a  shadow-path  that  is  also  unbroken  and 
continuous.  This  is  possible  only  if  we  assume  the  two  points 
at  infinity  to  be  connected,  that  is,  if  we  consider  them  identi- 
cal. This  assumption  will  seem  more  natural  if  we  reason  as 
follows.  In  the  profile-picture  the  table  is  represented  as  a 
straight  line,  and  it  is  along  this  fine  that  the  shadow  travels. 
We  may  regard  this  line  as  an  infinitely  great  circle,  for  an 
infinitely  great  circle  has  zero  curvature,  just  as  the  straight 
line,  from  which  it  is  therefore  indistinguishable.  The  in- 
finitely great  circle  has,  however,  only  one  point  situated  at  an 
infinite  distance,  that  is,  it  associates  together  the  two  apparent 
points  at  infinity  of  the  straight  fine  with  which  we  identify 
it.  Accordingly,  we  preserve  the  continuity  of  the  shadow- 
journey,  too.  Einstein  considers  it  allowable  to  say  that  the 
right  and  the  left  portion  each  represent  a  half  of  the  infinite 
projection,  which  becomes  complete  only  when  the  two  ends 
are  joined.] 

Now  we  must  be  prepared  for  an  effort  of  thought  which 


126  EINSTEIN  THE  SEARCHER 

will  need  considerable  help  from  our  imaginations.  Firstly, 
instead  of  one  surface-creature,  we  shall  suppose  several  crawl- 
ing about  on  different  meridians,  so  that  a  series  of  shadows 
will  be  moving  about  along  straight  Hues  radiating  from  the 
South  Pole.  Next,  let  us  imagine  the  whole  picture  to  have 
its  dimensions  increased  by  one,  that  is,  we  transform  the 
plane-picture  into  a  space  model.  The  phenomena  are  to 
remain  the  same,  except  that  they  are  to  be  strengthened  by 
one  dimension,  surface  conditions  becoming  space  conditions, 
and  surfaces  becoming  solids. 

What  we  now  see  are  actual  insects  with  round  bodies  (if 
we  retain  our  original  type  of  creatures),  or,  since  there  is  no 
restriction  as  to  their  size — the  shadows  have  assumed  all 
possible  sizes — we  may  assume  any  solid  bodies  whatsoever, 
stars  or  even  star-systems.  Their  motions  take  place  in  ex- 
actly the  same  way  as  those  of  the  shadows  previously  thrown 
by  the  flat  bodies. 

This  means  that,  if  a  stellar  body  moves,  its  size  increases 
until  it  reaches  the  spherical  boundary  of  space,  where  it 
becomes  infinitely  great,  and,  at  the  same  moment,  passes 
from  plus  infinity  to  minus  infinity,  that  is,  it  enters  the  uni- 
verse from  the  opposite  direction  ;  then,  if  it  continues  moving 
in  its  original  direction  (as  it  has  been  doing  all  along),  it 
gradually  becomes  smaller  in  size  until,  finally,  it  reaches  its 
original  position  and  its  original  size.  If  we  suppose  the  body 
to  be  endowed  with  the  power  of  sensation,  it  would  not  be 
able  to  observe  its  own  changes  of  size,  since  all  its  scale- 
measures  would  be  altered  in  the  same  proportion.  This 
whole  complex  of  phenomena  would  still  be  taking  place  in  an 
infinite  world  of  space,  but,  according  to  the  General  Theory 
of  Relativity,  the  geometry  that  is  vaUd  in  this  world  would 
no  longer  be  that  of  EucHd ;  it  is  replaced  by  a  system  of 
laws  that  arise  from  physics  as  a  geometric  necessity.  In  this 
new  geometry,  a  circle  described  with  unit  radius  is  a  little 
smaller  than  it  would  be  in  Euclidean  geometry,  with  the 
result  that  the  greatest  conceivable  circle  in  this  world  cannot 
assume  an  infinite  size. 

Thus  we  have  to  imagine  that  our  soHd  bodies,  say  stars, 
arrive  at  a  point  in  their  travels  which  we  may  term  only 
"enormously  distant."     If  we  call  the  directions  right  and 


OF  DIFFERENT  WORLDS  127 

left  instead  of  positive  and  negative,  then  the  process  reduces 
itself  to  this  :  the  moving  body  reaches  the  point,  which  is 
enormously  distant  on  the  right,  and  which  is  identical  with 
the  point  enormously  distant  on  the  left ;  this  means  that 
the  body  never  moves  out  of  the  space  continuum  of  this 
world,  but  returns  to  its  initial  point  of  departure  even  when 
it  moves  ever  onward  in  what  is  apparently  a  straight  line. 
It  moves  in  a  "  warped  "  space. 

Einstein  has  succeeded  in  finding  an  approximate  value 
for  this  non-infinite  universe,  from  the  fact  that  there  is  a 
determinable  gravitational  constant.  In  the  constitution  of 
the  universe  it  denotes  the  same  for  the  mass-relationships  of 
the  earth  as  the  gravitational  constant  of  the  earth  denotes  for 
us,  namely,  the  quantity  from  which  we  can  calculate  the  final 
velocity  attained  by  a  freely  falUng  body  during  a  unit  of 
time.  He  also  assumes  a  probable  average  for  the  density  of 
distribution  of  matter  in  the  universe,  by  supposing  that  it  is 
about  the  same  as  that  of  the  Milky  Way.  On  this  basis 
Einstein  has  arrived  at  the  following  result  by  calculation  : 

The  whole  universe  has  a  diameter  of  loo  million  Hght- 
years,  in  round  numbers.  That  amounts  to  about  700  triUion 
miles. 

M. :  Does  this  follow  from  the  discussion  you  entered  on 
just  now  ? 

Einstein  :  It  follows  from  the  mathematical  calcula- 
tions which  I  presented  in  "  Cosmological  Considerations  arising 
from  the  General  Theory  of  Relativity,"  in  which  the  figure  I 
have  just  quoted  is  not  given.  The  exact  figure  is  a  minor 
question.  What  is  important  is  to  recognize  that  the  imi verse 
may  be  regarded  as  a  closed  continuum  as  far  as  distance- 
measurements  are  concerned.  Another  point,  too,  must  not 
be  forgotten.  If,  in  deference  to  your  wish,  I  used  an  easy 
illustration,  this  must  not  be  regarded  otherwise  than  as  an 
improvised  bridge  to  assist  the  imagination. 

M. :  Nevertheless,  it  will  be  very  welcome  to  many,  who 
are  unable  to  grasp  the  difficult  Cosmological  Considerations. 
The  number  that  you  mention  is  overwhelming  in  the  extreme. 
Indeed,  it  seems  to  me  that  a  diameter  of  100  milUon  fight - 
years  suggests  an  infinitely  great  distance  more  than  the  word 
"  infinity  "  itself,  mentioned  per  definitionem,  which  conveys 


128  EINSTEIN  THE  SEARCHER 

nothing  to  the  ordinary  mind.  It  calls  up  a  regular  carnival 
of  numbers,  particularly  in  those  to  whom  the  immense  number 
alone  gives  a  certain  pleasure.  But  you  were  going  to  give  me 
the  number  expressing  the  mass,  too  ?  " 

And  then  I  learned  that  the  weight  of  the  whole  universe, 
expressed  in  grammes,  was  lo  multiplied  by  itself  54  times, 
that  is  10^*  (453  grammes  =  I  lb.,  roughly).  This  seems 
rather  disappointing  at  first,  but  assumes  a  different  aspect 
when  we  represent  to  ourselves  what  this  figure  signifies.  It 
means  that  the  weight  of  the  universe  in  kilogrammes  is  high 
in  the  octillions.  The  earth  itself  weighs  six  quadrilUon  kilo- 
grammes, hence  the  weight  of  the  Einstein  universe  bears 
the  same  relation  to  the  weight  of  the  whole  earth  as  the  latter 
bears  to  a  kilogramme.  Again,  the  earth's  weight  to  that  of 
the  sun  is  as  i  is  to  324,000.  Hence  we  should  have  to  take  at 
least  a  trillion,  that  is,  a  milliard  times  a  milliard,  suns  to  get 
the  weight  of  the  universe.  And  as  far  as  the  linear  extent  is 
concerned,  let  us  consider  the  most  distant  stars  of  the  Milky 
Way,  which  are  at  an  inconceivable  distance,  expressible  only 
in  light-years.  If  we  place  10,000  such  Milky  Ways  end  to 
end  we  shall  arrive  at  this  diameter  of  the  universe,  which, 
accordingly,  will  have  a  cubical  content  a  thousand  milliard 
times  greater  than  the  region  accessible  to  astronomical 
observation. 

Thus  we  have  a  very  spacious  universe.  Yet  it  is  not 
spacious  enough  to  satisfy  all  the  demands  that  a  mathe- 
matician interested  in  permutations  and  combinations  might 
make.  One  of  such  combinations  is  exemplified  in  the  so- 
called  Universal  Book,  that  originated  in  an  imaginary 
experiment  of  Leibniz.  If  we  picture  to  ourselves  the  sum- 
total  of  all  books  that  can  be  printed  by  making  all  possible 
arrangements  and  successions  of  our  letters,  each  book  differ- 
ing from  any  other  even  if  only  in  one  symbol,  then,  together, 
they  must  contain  all  that  can  be  expressed  in  sense  and  non- 
sense, and  everything  that  is  ever  reahzable  actually  or  in 
dreams.  Hence,  among  other  things,  they  would  include  all 
world-history,  all  literature,  and  all  science,  even  from  the 
beginning  of  the  world  to  the  end.  If  we  agree  to  the  con- 
vention of  operating  with  100  different  printed  signs  (letters, 
figures,  stops,  spacings,  etc.),  and  of  allowing  each  such  book  a 


OF  DIFFERENT  WORLDS  129 

million  paces  for  signs,  so  that  each  book  will  still  be  of  a  handy 
size,  then  the  number  of  these  books  would  amount  to  exactly 
10  to  the  two-miUionth  power,  or,  in  figures,  i.e.  zo^'^^'^^. 

This  fully  exhaustive  universal  library  containing  all 
wisdom  would  consist  of  so  many  volumes  that  it  could  not  be 
contained  in  a  case  of  the  size  of  the  entire  stellar  universe. 
And,  unhappily,  it  must  be  added  that  the  closed  universe, 
just  described  by  Einstein  and  having  a  diameter  of  a  hundred 
million  light-years  would  be  much  too  small  to  contain  this 
library. 

"  Nevertheless,"  said  I,  "  your  universe  pictures  something 
inconceivably  great ;  one  might  call  it  an  infinity  expressed 
in  figures.  For  in  your  world  there  still  remains  one  property 
of  infinity,  namely,  that  it  imposes  no  limitations  on  motion  of 
any  kind.  On  the  other  hand,  the  figures  proclaim  a  Umited 
measure  in  the  mathematical  sense,  however  great  this  measure 
may  be.  This  calls  up  the  old  restlessness  of  mind,  due  to 
the  persistent  question :  What  Hes  beyond  ?  The  absolute 
Nothing  ?  Or  is  it  a  something  which  yet  does  not  occupy 
space  ?  Descartes  and  many  other  great  thinkers  have  never 
overcome  this  difficulty,  and  have  always  afiirmed  that  a 
closed  world  is  impossible.  How,  then,  is  the  average  person 
to  reconcile  himself  with  the  dimensions  you  have  estab- 
Hshed  ? " 

Einstein  gave  an  answer  which,  it  seemed  to  me,  offered  a 
last  escape  to  apprehensive  minds.  "It  is  possible,"  so  he 
said,  "  that  other  universes  exist  independently  of  our  own." 

That  is  to  say,  it  will  never  be  possible  to  trace  a  connexion 
between  them.  Even  after  an  eternity  of  observation,  calcula- 
tion, and  theoretical  investigation,  no  glimpse  or  knowledge 
of  any  of  these  ultra-worlds  will  ever  enter  our  consciousness. 
"  Imagine  human  creatures  to  be  two-dimensional  surface- 
creatures,"  he  added,  '*  and  that  they  Uve  on  a  plane  of  in- 
definite extent.  Suppose  that  they  have  organs,  instruments, 
and  mental  attitude  adapted  strictly  to  this  two-dimensional 
existence.  Then,  at  most,  they  would  be  able  to  find  out  all 
the  phenomena  and  relationships  that  objectify  themselves  in 
this  plane.  They  would  then  have  an  absolutely  perfect  science 
of  two  dimensions,  the  fullest  knowledge  of  their  cosmos. 
Independent  of  this,  there  might  be  another  cosmic  plane  with 
9 


130  EINSTEIN  THE  SEARCHER 

other  phenomena  and  relationships,  that  is,  a  second  analogous 
universe.  There  would  then  be  no  means  of  constructing  a 
connexion  between  these  two  worlds,  or  even  of  suspecting 
such  a  connexion.  We  are  in  just  the  same  position  as  these 
plane-inhabitants  except  that  we  have  one  dimension  more. 
It  is  possible,  in  fact,  to  a  certain  degree  probable,  that  we 
shall  by  means  of  astronomy  discover  new  worlds  far  beyond 
the  limits  of  the  region  so  far  investigated,  but  no  discovery 
can  ever  lead  us  beyond  the  continuum  described  above,  just 
as  little  as  a  discoverer  of  the  plane-world  would  ever  succeed 
in  making  discoveries  beyond  his  own  world.  Thus  we  must 
reckon  with  the  finitude  of  our  universe,  and  the  question  of 
regions  beyond  it  can  be  discussed  no  further,  for  it  leads 
only  to  imaginary  possibilities  for  which  science  has  not  the 
slightest  use." 

Einstein  left  me  for  a  while  to  the  tumult  of  ideas  that  he 
had  roused  up  in  me.  After  I  had  overcome  the  first  shock,  I 
sought  to  gain  a  haven  in  the  idea  that  arose  out  of  the  first 
shadow-argument,  in  which  the  spherical  bodies  occurred  that 
seek  to  escape  towards  infinity  on  the  right  but  reappear,  in- 
stead, at  enormous  distances  on  the  left.  Has  anyone  ever  had 
presentiments  of  this  kind  of  world  ?  Perhaps  something  of 
the  sort  is  to  be  found  in  earUer  books  of  science  ?  If  so,  they 
have  escaped  my  notice.  Yet,  a  passage  of  a  poet  occurs  to 
me.  It  is  to  be  found  in  a  volume  by  Heinrich  von  Kleist  ; 
it  is  a  volume  dealing  only  with  earthly  matter  and  bare  of 
astronomical  ideas.  Imagine  a  book  the  subject  of  which 
is  a  puppet-show,  containing,  in  the  middle  of  it,  a  section 
foreshadowing  Einstein's  universe  !  Quite  by  chance  Kleist 
comes  to  speak  of  "  the  intersection  of  two  lines  which,  after 
passing  through  infinity,  suddenly  appear  on  the  other  side, 
like  a  picture  in  a  concave  mirror,  which  moves  away  to  infinity 
and  suddenly  returns  again  and  is  quite  close,"  and,  quite  in 
accordance  with  our  new  cosmology,  he  declares  :  "  Paradise 
is  locked  and  barred,  and  the  cherub  is  behind  us ;  we  must 
make  a  voyage  round  the  world,  and  see  whether  we  cannot 
discover  an  exit  elsewhere  at  the  other  end  perhaps." 

Perhaps  poets  of  the  future  will  busy  themselves  with  this 
universei  not  lyrical  poets,  but  descendants  of  Hesiod^  Lucretius, 


OF  DIFFERENT  WORLDS  131 

or  Rtickert.  They  will  express  in  verse  that  Einstein's  world 
offers  a  source  of  consolation  to  tormented  spirits  which  have 
sickened  of  Kant's  antinomies.  For  in  this  still  almost  im- 
measurable world  the  fateful  conception  **  infinite  "  has  been 
made  bearable  for  the  first  time.  In  a  certain  way  it  reHeves 
us  from  what  is  quite  inconceivable,  yet  into  which  we  are 
usually  driven,  and  forms  a  bridge  between  the  thesis  "  finite  " 
and  the  antithesis  infinite.  We  are  brought  to  a  common 
stream,  in  which  both  conceptions  peacefully  flow  together. 
There  was  no  mention  of  this  in  our  talk,  and  I  had  good  reason 
for  being  cautious  about  following  out  the  theme  along  these 
lines.  I  must  not  allow  any  doubts  to  arise  on  this  point  : 
Einstein,  himself,  clings  with  unerring  logic  to  the  strict 
mathematically  defined  conception  of  infinity,  and  allows 
no  compromise  with  the  non-infinite. 

When  I,  on  some  previous  occasion,  sought  to  lead  him  on 
to  a  compromise,  involving  a  transition-boundary,  it  availed 
me  nothing  that  I  quoted  Helmholtz  to  support  the  possibility 
of  such  an  operation  :  my  effort  came  to  an  abrupt  end. 

In  pursuing  these  considerations  about  the  universe,  we 
arrived  at  things  which,  in  ordinary  language,  are  usually  called 
"  occult."  In  connexion  with  this,  these  remarks  ensued  : 
"  I  am,  of  course,  far  from  trying  to  trace  out  a  connexion 
between  the  four-dimensionality  that  you  estabUsh,  Professor, 
and  the  four-dimensionality  of  certain  spiritistic  pseudo- 
philosophers,  yet  it  suggests  itself  to  me  that  in  such  occult 
circles  efforts  will  be  made  to  derive  advantage  from  the  fact 
that  the  same  word  is  used  in  both  cases.  This  is  more  than  a 
conjecture,  indeed,  for  there  are  no  misgivings  among  the 
ignorant,  and  so  we  actually  find  the  name  Einstein  quoted  in 
connexion  with  mediumistic  experiments  that  are  flavoured 
with  four-dimensionality." 

"  It  will  not  be  expected  of  me,"  said  Einstein,  "  to  enter 
into  discussion  with  ignoramuses  and  misinterpreters.  Dis- 
carding them,  then,  let  us  confine  ourselves  to  a  brief  con- 
sideration of  the  conception  '  occult,'  as  this  has  played  a  part 
in  serious  science.  The  chief  example  of  this  in  history  is 
gravitation.  Huyghens  and  Leibniz  refused  to  accept  gravita- 
tion, for,  so  they  said,  according  to  Newton's  view,^it  is  an 


132  EINSTEIN  THE  SEARCHER 

action  at  a  distance  and  hence  belongs  to  the  realm  of  the 
occult.  Like  everything  occult,  it  contradicts  the  causal 
order  in  Nature.  We  must  not  regard  Huyghens'  and  Leib- 
niz's contradiction  as  being  due  to  lack  of  perspicacity  ;  rather, 
they  objected  on  grounds  which,  as  investigators,  they  had 
every  right  to  uphold.  For,  as  far  as  our  everyday  experience 
is  concerned,  every  mutual  influence  of  things  in  Nature  occurs 
only  by  direct  contact,  as  by  pressure  or  impact,  or  by  chemical 
action,  as  when  a  flame  is  lit.  The  fact  that  sound  and  Hght 
apparently  form  exceptions  is  not  usually  felt  as  a  contradiction 
to  the  postulate  of  contact.  The  case  of  a  magnet  appears 
much  more  striking  because  its  effect  asserts  itself  as  a  direct 
manifestation  of  force.  I  must  mention  that  when  I,  as  a  child, 
made  my  first  acquaintance  with  a  compass — and  this  was 
before  I  had  ever  seen  a  magnet — it  created  a  sensation  in  me, 
which  I  consider  to  have  been  a  dominant  factor  in  my  hfe  up 
to  the  very  present.  There  is,  indeed,  a  fundamental  difference 
between  pressure  and  impact  on  the  one  hand,  and  what  we 
hear  and  see  on  the  other,  even  in  everyday  experience.  In 
the  case  of  Hght  and  sound,  something  must  be  '  happening  ' 
continually,  if  the  effect  is  to  occur  and  continue.  .  ,  ." 

"  Yet  another  difference  seems  to  enter  here,''  I  interposed. 
"  Is  it  possible  to  give  a  full  explanation  of  gravitation  by  using 
only  the  conceptions  pressure  and  impact  ?  Perhaps  *  pressure 
at  a  distance  '  would  not  have  seemed  to  contemporaries  of 
Newton  as  unintelligible  as  a  'tension  or  pull  at  a  distance.' 
It  seems  to  me  that  it  is  particularly  difficult  to  imagine  a  pull 
or  an  attraction  towards  a  distant  object." 

Einstein  does  not  consider  this  difference  considerable,  and 
regards  it  as  possible  to  overcome  it  even  in  a  manner  which 
can  be  directly  pictured.  "  If  the  force  is  exerted  by  a  corpus- 
cular transmission,"  he  explained,  "  we  may  imagine  a  '  force- 
shadow  '  into  which  the  bombarding  corpuscles  cannot  pene- 
trate. Thus  if  an  obstacle,  which  produces  such  a  shadow, 
becomes  interposed  between  a  body  A  and  a  body  B,  then  there 
will  be  a  lesser  pressure  on  the  side  of  B  facing  A,  and  hence 
B  will  experience  a  greater  corpuscular  pressure  on  the  other 
side,  with  the  result  that  B  will  be  forced  in  the  direction  of  A, 
and  the  observer  would  gain  the  impression  of  a  pull  from  B 
to  A.     Nowadays,  when  the  theory  of  *  fields  of  force  '  domin- 


OF  DIFFERENT  WORLDS  183 

ates  our  physical  views,  we  need  trouble  just  as  little  about 
using  corpuscular  pressures  and  impacts  as  about  the  vortices 
which  Descartes  once  considered  as  the  ultimate  causes  of  the 
motions  of  the  heavenly  bodies.  The  efforts  of  certain 
reformers  to  reintroduce  these  vortices  and  whirlpools  as 
explanations  must  be  regarded  as  futile.** 

"  Nevertheless,"  I  answered,  *'  it  seems  admissible  to  say 
that,  ultimately,  there  is  always  an  occult  element  in  every 
physical  explanation,  an  absolutely  final  and  elementary 
something  which  we  recognize  as  a  principle,  without  conceaUng 
from  ourselves  that  we  have  reached  the  Umit  of  explanation, 
and  our  knowledge  avails  no  further.  This  brings  me  to 
another  question  the  discussion  of  which,  as  I  clearly  perceive, 
leads  us  on  to  dangerous  ground.'* 

Einstein  :  Don't  hesitate  to  say  what  is  troubling  you. 
I  cannot  yet  see  what  you  are  aiming  at. 

M.  :  I  am  referring  to  certain  phenomena  which  are  also 
called  *'  occult  " — with  the  object  of  discrediting  them.  They 
may  at  times  degenerate  to  hocus-pocus  and  fall  into  the  cate- 
gory of  dubious  arts.  It  seems  to  me,  however,  that  scientists 
have  not  always  drawn  the  line  with  sufficient  care,  and  that 
they  have  been  disposed  to  reject  as  humbug,  without  examina- 
tion, everything  inexplicable  that  dares  to  present  itself  in  the 
form  of  open  display. 

Einstein  :  In  general,  they  will  be  in  the  right,  for  investi- 
gators cannot  be  expected  to  occupy  themselves  with  things 
bolstered  up  by  advertisement,  and  which  are  supposed  to  be 
connected  with  some  fabulous,  occult  regions. 

M. :  Nevertheless,  in  my  opinion  even  among  such  displays 
there  sometimes  occur  phenomena  which  scientists  should  not 
pass  over  with  contempt.  I,  myself,  have  experienced  such 
cases,  and  have  said  to  myself  :  There  are  stranger  happenings 
here 

Einstein  :  — than  are  dreamt  of  in  your  philosophy,  you 
were  about  to  say  ? 

M. :  Exactly.  These  are  things  that  in  the  guise  of  sensa- 
tionalism often  hide  a  physical  truth  well  worthy  of  study. 

Einstein  :  But  you  must  not  overlook  the  fact  that  in  such 
cases  you  have  mostly  played  the  part  of  an  onlooker,  and  hence 
were  exposed  to  all  possible  manner  of  deception.     You  are 


134  EINSTEIN  THE  SEARCHER 

baffled  on  all  sides  by  undiscoverable  tricks  and  by  other 
persons,  whose  collusion  you  do  not  suspect.  This  renders 
an  objective  criticism  impossible. 

M.  :  This  presumes  that  the  performing  artist  is  not  entirely 
isolated.  It  is  possible  to  bring  about  conditions  that  posi- 
tively eliminate  all  tricks  from  the  very  outset. 

Einstein  :  If  you  have  experienced  any  such  cases,  relate 
them  by  all  means. 

M.  :  I  shall  be  brief,  and  shall  state  only  facts.  .  .  . 

Einstein  :  Or,  expressed  more  accurately,  only  things 
which  seem  to  have  been  facts  as  far  as  you  can  trust  to  memory. 
Well  then,  you  think  that  you  have  grounds  for  saying  that 
you  caught  a  glimpse  of  a  mysterious  world  at  that  time. 

M.  :  It  is  certainly  long  ago,  more  than  thirty  years. 
Hansen,  the  freak,  one  of  the  most  eminent  of  his  profession, 
was  showing  hypnotic  and  telepathic  experiments  that  were 
partly  identical  with  experiments  that  the  celebrated  scientist 
Charcot  at  Paris  was  performing  for  purposes  of  pathology. 

Einstein  :  Well,  then,  why  did  you  hesitate  before  ?  These 
experiments  come  under  the  head  of  science,  and  require  no 
occult  veil  to  appear  in  the  open. 

M. :  This  touches  the  main  issue.  Hansen  did  not  work 
in  the  interests  of  science,  but  wished,  above  all,  to  earn  money. 
Nevertheless  he  had  in  his  own  way  produced  marvellous 
results  that  were  used  later  for  scientific  work.  Unfortun- 
ately in  his  case,  owing  to  the  fact  that  he  cloaked  it  in  occultism 
at  the  outset,  he  was  brusquely  repudiated  by  scientists.  The 
result  was  that  Hansen  was  condemned  to  a  long  period  of 
imprisonment  in  Dresden,  thanks  to  the  recommendation  of 
scientists  who  declared  that  the  experiments  were  only  possible 
if  deception  was  practised,  and  hence  that  Hansen  was  an 
impostor  who  should  be  made  harmless  by  being  incarcerated. 

Einstein  :  And  how  did  you  yourself  seek  to  discover 
whether  his  experiments  were  genuine  ? 

M.  :  Very  easily  and  with  absolute  certainty.  One  of  my 
acquaintances,  the  wealthy  race-horse  owner,  von  Oelschlager, 
had  induced  him  by  means  of  a  high  fee  to  experiment  at  his 
country  house,  at  some  distance  from  BerUn,  in  the  presence 
of  persons,  not  one  of  whom  Hansen  knew,  and  in  the  case  of 
whom  there  could  be  no  question  of  secret  collaboration.    I  can 


OF  DIFFERENT  WORLDS  185 

assure  you  that  everything  succeeded  without  exception.  A 
single  second  was  sufficient  for  him  to  communicate  his  will 
to  each  subject  of  experiment.  He  operated  Hke  a  super- 
natural being  on  those  present. 

Einstein  :  I  should  hke  to  hear  examples. 

M. :  Herx  von  Oelschlager  introduced  four  jockeys,  and 
suggested  a  race  in  the  great  salon.  Hansen  placed  them 
astride  over  chairs,  hypnotized  them  on  the  spot,  described 
the  shape  of  the  course,  giving  distances  in  kilometres,  curves, 
and  even  the  value  of  the  prizes.  He  then  gave  the  signal 
for  starting.  The  jockeys  immediately  began  treating  their 
chairs  as  race-horses,  exhibiting  all  the  signs  of  extreme 
strain  which  accompany  the  actual  ride. 

Einstein  :  This  is  not  yet  a  positive  proof.  The  subjects 
of  experiment  may  have  become  cognizant  of  the  fact  that 
they  were  to  serve  some  eccentric  display.  Their  acquiescence 
in  a  prescribed  part  need  by  no  means  signify  that  they  were 
subjectively  convinced  of  the  genuineness  of  the  affair. 

M.  :  There  could  be  not  the  shghtest  doubt  on  this  point. 
After  a  few  seconds  perspiration  was  streaming  over  their 
faces  as  a  result  of  the  exertion,  a  symptom  that  exhibits 
itself  only  when  the  participants  are  convinced  of  the  absolute 
earnestness  of  their  undertaking.  All  that  gazed  on  this 
baffling  ride  made  the  acquaintance  of  a  grotesque  reahty, 
and  were  looking  into  a  strange  world  of  dreams,  which  trans- 
formed wooden  chairs  into  hving  thoroughbreds.  In  the 
course  of  his  following  experiments  in  the  transference  of  his 
will-power,  Hansen  experimented  with  an  actress  who  was 
famous  at  that  time,  and  with  whom  he  had  no  more  acquaint- 
ance than  with  the  others.  He  again  produced  deep  hypnosis, 
and  gave  the  order  :  I  shall  ask  you  various  questions,  all  of 
which  you  will  be  able  to  answer  correctly,  with  one  exception : 
you  will  have  forgotten  your  name.  And  so  it  happened. 
In  her  trance  the  actress  gave  correct  answers,  until,  when 
the  question,  "  What  is  your  name  ?  "  was  asked,  her  own 
name,  Helene  Odilon,  had  vanished  from  her  memory.  And 
immediately  afterwards,  she  told  me  herself  that,  in  spite  of 
her  state  of  coma,  she  had  retained  full  consciousness,  had 
understood  everything,  and  had  been  possessed  of  her  memory 
until  it  came  to  the  critical  moment  when,  in  spite  of  extreme 


136  EINSTEIN  THE  SEARCHER 

efforts,  she  could  not  recollect  the  words  Helene  Odilon. 
But  Hansen  did  not  stop  at  dictating  his  thoughts  to  others, 
he  also  transformed  corporate  things.  By  a  single  motion 
of  his  hand  he  converted  a  stable-boy  into  a  rigid  block, 
devoid  of  sensation.  Never  would  I  have  thought  such  an 
intense  state  of  cramp  possible.  He  placed  the  boy  with 
his  feet  and  head  alone  resting  on  two  supports,  so  that  the 
body  itself  was  poised  in  space.  He  then  stood  on  the  body 
with  his  whole  weight,  without  the  rigid  body  of  the  boy 
bending  even  an  inch. 

Einstein  :  How  did  he,  in  all  these  cases,  restore  the 
normal  state  ? 

M.  :  Always  by  a  single  gesture,  which,  like  everything 
that  he  did,  worked  at  lightning  speed.  I  must  admit  that 
his  display  became  a  little  monotonous  after  a  while,  and 
that  his  programme  did  not  seem  capable  of  much  variation. 
Things  were  different,  however,  in  the  case  of  a  man  who, 
some  years  previously,  had  toured  the  world  as  an  exponent 
of  occult  phenomena,  and  to  whom  scientists  will  some  time 
in  the  future  look  back  with  regret.  When  he  appeared, 
most  academicians  took  only  sufficient  notice  of  him  to  reject 
him  without  having  given  him  a  trial.  It  was  Henry  Slade, 
the  American,  who  is  not  to  be  confused  with  other  Slades 
who  appropriated  his  name  in  order  to  dupe  people  whose 
insatiable  curiosity  was  aroused. 

Einstein  :  One  might  almost  suppose  that  your  genuine 
Henry  Slade  served  as  a  model  for  them. 

M.  :  For  certain  reasons  I  regard  this  as  out  of  the  question, 
mainly  because  the  true  Slade  gave  "  demonstrations  "  only 
occasionally,  his  chief  object  being  to  interest  scientists.  He, 
himself,  repeatedly  asserted  that  he  did  not  understand  his 
own  achievements,  and  he  unceasingly  requested  the  super- 
vision of  professional  physicists  and  physiologists,  to  whom 
the  unusual  phases  in  his  nature  were  to  serve  as  objects  of 
study.  The  result  was  that  people  Hke  Dubois-Reymond, 
Helmholtz,  and  Virchow  refused  to  see  him,  not  to  mention 
experiment  with  him. 

Einstein  :  These  men  cannot  be  reproached  for  acting  in 
this  way.  Slade  was  regarded  as  a  representative  of  a  four- 
dimensional  world  in  the  spiritistic  sense ;    serious  scientists 


OF  DIFFERENT  WORLDS  137 

must  avoid  all  humbug  of  this  sort,  since  even  slight  interest 
in  it  can  easily  be  misinterpreted  by  the  ignorant  pubHc. 

M. :  Not  every  one  was  afraid  of  compromising  himself. 
After  closed  doors  had  greeted  Slade  in  Berhn,  he  went  to 
Leipzig,  where  he  became  an  object  of  study  for  one  important 
scientist. 

Einstein  :  You  are  referring  to  Friedrich  Zollner,  who 
undoubtedly  had  a  reputation  as  an  astrophysicist  to  preserve. 
But  he  would  have  served  his  reputation  better  if  he  had  not 
entered  into  this  adventure  with  the  American  spiritist. 

M.  :  Perhaps  there  will  some  day  be  cause  for  a  revision 
of  opinion  on  this  point.  The  documents  are  extant,  even  if, 
half  forgotten,  they  are  reposing  in  various  Hbraries.  A 
renewed  investigation  of  Zollner's  Scientific  Dissertations, 
dating  from  1878  to  1891,  might  lead  to  the  judgment  that 
his  ghostly  interpretations  are  to  be  regarded  as  occult  in 
the  worst  sense,  and  yet  one  would  marvel  that  a  great  scientist, 
such  as  he  was,  should  have  felt  himself  at  a  complete  loss 
with  his  knowledge,  so  that  he  was  forced  to  resort  to  abstruse 
methods  in  order  to  escape  from  the  mental  confusion  into 
which  Slade  had  plunged  him. 

Einstein  :  That  merely  shows  that  Slade,  as  a  cunning 
practician,  siupassed  him,  and  that  Zollner  did  not  succeed 
in  seeing  through  his  machinations. 

M.  :  This  would  lead  one  to  assume  that  Slade  knew  more 
physics  than  the  Leipzig  professor.  For  in  a  great  number  of 
experiments  Zollner  himself  had  prescribed  the  conditions, 
including  all  contrivances  which  made  deception  so  much 
the  more  unhkely,  since  Slade  himself  could  not  know  what 
Zollner's  intentions  were.  It  was  a  question  of  Electricity, 
Magnetism,  Optics  including  prepared  conditions  of  polariza- 
tion, involved  Mechanics,  in  short,  things  that  Zollner  as 
a  professional  physicist  imderstood  thoroughly,  and  which, 
moreover,  were  controlled  by  others  of  his  profession.  Among 
the  latter  was  the  celebrated  professor  of  Electricity,  Wilhelm 
Weber,  who,  hke  Zollner,  found  himself  faced  by  phenomena 
that  were  utterly  incomprehensible  to  him.  It  would  be  a 
profitable  undertaking  to  bring  these  dissertations  to  hght 
again,  and  it  would  easily  be  recognized  that  the  things  de- 
scribed actually  deal  with  scientific  problems  and  have  not 


138  EINSTEIN  THE  SEARCHER 

the  remotest  connexion  with  tricks  of  magic.  For  example, 
there  is  an  account  of  an  incredible  anatomical  feat.  On 
flour  which  had  been  placed  carefully  in  a  dish  beforehand, 
there  suddenly  appeared  the  imprint  of  a  naked  human  foot, 
whilst  Slade  was  present  at  a  certain  distance,  being  fully 
clothed  and  subject  to  careful  scrutiny.  The  footprint 
showed  all  the  surface-details  of  the  skin,  as  was  confirmed  by 
authorities,  just  as  only  a  left  foot  could  produce  them,  but 
not  an  artificial  copy. 

Einstein  :  And  from  this  Zollner  inferred  the  intervention 
of  supernatural  beings  ?  He  would  have  done  better  to 
measure  the  dimensions  of  the  foot. 

M.  :  So  he  did — at  once.  A  difference  of  four  centimetres 
between  the  length  of  Slade's  foot  and  the  copy  was  disclosed. 
This  riddle,  like  so  many  others,  remained  unexplained.  I 
must  repeat  that  I  am  not  in  the  slightest  degree  disposed 
to  assert  that  occult  phenomena  really  occur,  but  am  interested 
only  in  seeing  that  they  are  investigated  carefully  by  qualified 
persons. 

Einstein  :  Your  remarks  show  that  Leipzig  scientists 
did  so  at  that  time  with  no  better  result  than  that  Zollner's 
mental  confusion  became  still  greater. 

M. :  The  conjecture  remains  that  the  Leipzig  experiments, 
abundant  as  they  were,  did  not  suffice.  Allow  me  to  ask  a 
direct  question,  Professor.  Supposing  another  such  agent  of 
miracles  should  appear,  would  you  yourself  feel  impelled  to 
test  him  experimentally  ? 

Einstein  :  Your  question  is  misdirected.  I  explained 
above  that  I  share  the  point  of  view  taken  up  by  Dubois- 
Reymond  and  his  colleagues. 

M. :  The  following  case  may  be  conceived.  A  certain  man, 
X,  might  suddenly  appear,  who  has  control  of  a  certain 
natural  force  that  has  never  before  been  investigated ;  like 
one  who  knew  how  to  use  electricity  at  a  time  when  people 
had  never  experienced  any  electrical  phenomenon.  He 
would  be  able  to  give  hundreds  of  demonstrations,  all  of  which 
we  should  relegate  to  the  realm  of  inexplicable  magic.  We 
should,  for  instance,  be  much  astonished  if  he  were  to  draw 
sparks  from  a  living  person.  Now,  suppose  two  professors 
express  an  opinion.     Professor  A  declares  the  whole  thing  to 


OF  DIFFERENT  WORLDS  139 

be  a  farce,  and  refuses  to  look  into  it  at  all.  Professor  B  is 
ready  to  investigate  the  achievements  of  X  only  if  the  latter 
subjects  himself  from  the  beginning  to  all  the  physical  condi- 
tions that  are  to  be  determined  beforehand.  And  suppose  the 
professor  arranges  liis  conditions  so  that  they  make  impossible 
the  occurrence  of  electrical  phenomena.  If,  now,  all  scientists 
were  to  behave  hke  A  and  B,  the  consequences  would  be  very 
depressing.  For  here  was  an  important  field  of  investigation, 
which  is  cut  off  owing  to  the  distrust  or  obstinacy  of  scientists, 
who  should  have  been  the  first  to  open  it  up.  It  is  quite 
irrelevant  whether  X  had  the  character  of  a  charlatan  or  not, 
for  behind  his  charlatanism  there  were  facts  which  clamoured 
for  investigation. 

Einstein  :  The  most  that  I  can  grant  is  that  your  imagined 
case  does  not  lie  outside  the  scope  of  possibility.  Yet  the 
chance  that  there  is  such  a  **  natural  force  "  hitherto  undis- 
covered by  Man,  that  is,  one  that  is  a  "  secret  force  *'  as  far  as 
we  are  concerned,  is  so  vanishingly  small  that  it  may  be  set 
down  as  equal  to  impossible.  I  should  refuse  to  take  part  in 
any  such  practices,  served  up  in  the  form  of  sensation,  for  one 
reason  that  I  should  regret  the  waste  of  time,  as  there  are 
better  things  to  do.  It  is  a  different  matter  if  the  mood  takes 
me  to  visit  a  variety  entertainment,  in  order  to  derive  amuse- 
ment from  such  mystifications.  For  example,  only  yesterday 
I  was  in  a  little  theatre,  in  which,  among  diverse  items,  a 
thought-reading  woman  was  performing.  She  correctly  guessed 
the  numbers  6i  and  59  that  I  had  in  my  mind.  But  let  no 
one  mention  this  as  a  case  of  telepathic  actions  at  a  distance 
or  wireless  communication  between  minds,  for  an  intermediate 
person,  the  manager,  was  present,  and  I  had  to  whisper  the 
numbers  to  him.  The  distance  to  the  stage  was  certainly 
too  great  to  allow  the  sound  to  be  conveyed  directly  to  an 
audible  degree.  Hence  there  must  have  been  a  different,  very 
cunningly  arranged  code  of  signals,  which  eluded  the  notice 
of  people  in  the  stalls.  The  process  consists  actually  in  an 
extraordinary  refinement  of  observation,  which  does  not, 
however,  seem  to  me  any  more  wonderful  than  the  training 
of  a  reckoner  who  extracts  cubic  roots  mentally,  or  than  the 
practised  muscles  of  a  juggler  all  working  in  unison  to  enable 
him  to  perform  feats  with  twelve  plates  simultaneously. 


140  EINSTEIN  THE  SEARCHER 

M. :  It  gives  me  enough  satisfaction,  Professor,  that  you 
conceded  me  before  a  certain  limited  chance  of  finding  a  last 
refuge  in  occultism.  And  even  if  you,  yourself,  as  a  representa- 
tive of  the  most  rigorous  research  of  physical  reality,  refuse  to 
consider  it,  yet  the  fact  that  many  others  are  drawn  irresistibly 
towards  mysterious  phenomena  cannot  be  denied.  Should 
one  feel  shame  on  this  account  ?  I  beUeve  that,  in  this  matter, 
we  are  touching  on  inner  confessions  that  are  quite  independent 
of  the  standard  of  the  mind  in  which  they  are  embedded. 
Newton  considered  the  key  of  the  universe  to  be  a  personal 
God,  whereas  Laplace  proclaimed  :  Dieu — -je  n'avais  pas  besoin 
de  cette  hypothese  :  this  contrast  allows  no  inference  to  be  drawn 
as  to  their  relative  keenness  of  mind.  And  probably  the  same 
may  be  said  of  the  question  whether  there  are  other  hidden 
universes  besides  the  one  in  which  we  Hve.  In  any  case,  those 
who  feel  enthusiasm  for  such  questions  can  quote  in  their  sup- 
port good  names  from  the  learned  world.  Immanuel  Kant 
occupied  himself  seriously  and  intensively  with  the  wonders  of 
Swedenborg,  Kepler  practised  Astrology,  in  which  he  had  a 
firm  belief,  Roger  Bacon,  Cardanus,  Agrippa,  Nostradamus, 
van  Helmont,  Pascal,  and,  among  the  modem,  Fechner, 
Wallace,  Crookes,  are  to  be  counted  among  the  mystics.  No 
matter  whether  the  views  they  held  were  theosophical,  occult, 
four-dimensional  in  the  spiritistic  sense,  or  coloured  by  any 
other  superstition  ;  they  proclaimed  that  things  that  could 
be  rigorously  proved  were,  alone,  insufficient  for  them.  Out  of 
presentiment  and  conjecture  they  constructed  wings  with  which 
to  fly  into  regions  extra  naturam.  This  is  how  it  happened  that, 
as  the  common  folk  could  not  find  a  place  in  science  for  many 
extraordinary  achievements,  they  assigned  their  authors  to  the 
realm  of  magicians,  as  in  the  case  of  Paracelsus,  Albertus 
Magnus,  Raimimdus  Lullus,  Sylvester  II,  who  were  regarded 
as  sorcerers.  And  this  coin  is  still  current  :  to  Edison,  of 
our  times,  the  term,  "  sorcerer  of  Menlo-Park,"  has  become 
attached.  In  the  minds  of  the  populace  discovery  and  in- 
vention, works  of  genius  and  supernatural  phenomena,  become 
confused  and  indistinguishable ;  it  may  even  happen  to  you. 
Professor,  that  your  works  will  become  invested  with  legend. 
I  should  not  like  to  conjure  up  what  your  fate  would  have  been 
if  your  theory  of  relativity  had  originated  at  the  time  of  the 


OF  DIFFERENT  WORLDS  141 

Inquisition.  For  the  views  put  forward  by  Giordano  Bruno 
are  mere  child's  play  compared  with  your  theory  of  the  universe 
as  a  quasi-spherical  closed  space  of  hyper-EucHdean  character. 
The  tribunal  of  the  Inquisition  would  not  have  imderstood 
your  differential  equation,  gravitational  potentials,  tensors, 
and  equivalence  theory ;  they  would  abruptly  have  declared 
the  whole  theory  to  be  a  magical  formula  or  a  manifestation 
of  the  devil,  and  would  have  honoured  it  and  you  with  a 
funeral  pyre. 

Einstein  :  This  is  clearly  a  slight  exaggeration.  Mathe- 
matico-physical  and  astronomical  works  have  never  been 
attacked  by  the  Papal  courts,  but,  on  the  contrary,  have  been 
much  encouraged  by  them  down  to  the  present  day.  This  is 
abundantly  clear  from  the  fact  that  we  can  set  up  a  whole  list 
of  Brothers  of  Orders,  particularly  Jesuits,  who  have  made 
eminent  discoveries  in  natural  science.  From  my  personal 
knowledge  of  you,  I  foresee  that  you  will  one  day  sketch  a 
fantastic  trial,  in  which  the  new  world-system  will  have  to 
defend  itself  against  the  Sanctum  Officium, 

M.  :  This  would  be  a  very  grateful  task,  judged  from  the 
literary  point  of  view.  What  a  splendid  colouring  could  be 
obtained  by  bringing  these  two  worlds  of  thought  into  conflict 
with  one  another,  the  Relative  against  the  Absolute,  which  has 
been  estabUshed  in  tradition  and  dogma.  But  we  need  not 
even  call  the  historical  fancy  into  action,  for,  actually,  the 
theory  of  the  structure  of  the  world  is  even  now  still  at  variance 
with  traditional  ideas,  that  act  with  dogmatic  violence.  There 
is  no  need  to  deny  the  fact  that  every  person  of  education,  who 
makes  the  acquaintance  of  Lorentz's,  Minkowski's,  Einstein's 
ideas  for  the  first  time,  feels  excited  to  offer  contradictions,  and 
becomes  involved  in  a  tumult  of  pros  and  cons,  and  each  one  ex- 
periences in  himself  the  excitement  of  an  inquisitorial  tribunal. 
The  triumph  of  the  new  theory  passes  over  the  corpses  of  con- 
ceptions that  He  at  the  cross-roads  of  thought  and,  long  after, 
retain  a  ghostly  existence.  Only  very  few  of  us  are  aware  of 
the  further  inner  revolution  that  awaits  us  along  the  hne  of 
development  of  Einsteinian  ideas  ;  we  have  only  vague  pre- 
sentiments that  whisper  to  us  that  the  end  of  forms  of  thought 
once  considered  as  irrefragable  is  drawing  nigh.  When  once 
the  principle  of  causaHty  has  been  set  on  a  relative  base,  and  all 


142  EINSTEIN  THE  SEARCHER 

"  properties  "  have  been  resolved  into  occurrence,  and  all  that 
is  three-dimensional  has  come  to  be  recognized  as  an  abstraction 
from  the  four-dimensional  world  that  is  alone  valid,  then  the 
time  will  have  come  to  arrange  for  the  death  procession  of  all 
the  philosophies  that  once  served  as  the  main  pillars  of  thought. 

A  retrospect  of  the  trials  of  Giordano  Bruno  and  of  Galileo 
GaUlei  offers  certain  parallels  other  than  those  usually  discovered 
by  scholars.  And  if,  to-day,  we  proclaim  Einstein  as  the  Galilei 
of  the  twentieth  century,  it  must  be  added  that  in  character  he 
is  fortunately  a  Bruno  and  not  a  GaHlei.  For  it  is  not  true 
that  the  latter  came  out  of  the  persecution  as  a  moral  victor 
with  an  eppur  si  muove,  rather,  in  spite  of  the  protection  of 
influential  prelates  and  dignitaries,  even  of  the  entourage  of 
the  Pope,  he  lacked  courage  and  bowed  his  head,  betraying 
his  science  and  denying  himself  as  well  as  Copernicus.  Are 
we  to  picture  how  Einstein  would  have  acted  under  similar 
circumstances,  even  if  they  cannot  recur  again  ? 

Whoever  has  even  an  inkling  of  his  character  will  entertain 
no  doubts.  At  that  time,  three  hundred  years  ago,  the  materials 
for  a  magnificent  scene,  "  one  world  versus  the  other,'*  lay  ready. 
Only  one  condition  was  wanting,  the  moral  courage  of  the  hero. 
The  lack  of  this  one  factor  spoilt  the  final  act  for  the  history  of 
that  time.  The  fine  ethical  feelings  of  later  generations  have 
had  to  be  propitiated  by  improvising  a  legend  iridescent  with 
beautiful  colours. 


m^^iS^nnt^SMT  OF  crVTL  EN^BIH^SEFIP^ 
BERKELEY.  CALJTORNIA 


CHAPTER  VII 
PROBLEMS 


Questions  of  the  Future. — Problem  of  Three  Bodies. — Conception  of 
Approximation. — Object  of  Mechanics. — Simplicity  of  Description. — Limits 
of  Proof. — Reflections  about  the  Circle. — From  the  History  of  Errors. — 
Causalities. — Relativity  on  a  Physiological  Basis. — ^Physicists  as  Philosophers. 

WE  Spoke  of  the  objects  and  problems  of  science  in 
general,  and  touched  on  certain  recurrent  questions 
with  which  reputed  men  of  science  are  confronted 
from  time  to  time,  so  that  we  may  ascertain  their  opinions  about 
immediate  as  well  as  more  remote  aims,  and  about  worthy 
objects  and  those  within  reach. 

"  Such  stimuh,"  said  Einstein,  "  may  be  quite  interesting 
inasmuch  as  they  sharpen  the  appetite  of  the  pubhc  for  the 
works  of  investigators,  and  give  the  latter  the  opportunity 
of  making  wider  circles  acquainted  with  their  plans.  Yet 
the  value  of  their  suggestions  must  not  be  overrated,  when 
they  are  directed  at  giving  trustworthy  information  about  the 
future  hues  of  development  of  science.  Every  scientist,  in 
working  out  his  own  research,  gravitates  to  particular  points 
on  the  boundary  which  separates  the  known  from  the  unknown, 
and  becomes  inchned  to  take  his  particular  perspective  from 
these  points.  It  must  not,  however,  be  expected  that  these 
individual  aspects  will  form  a  complete  picture,  and  will  indicate 
the  only  paths  along  which  science  can  or  will  advance.'* 

"  May  I  suggest,  Professor,"  I  answered,  *'  that  we  select 
certain  answers  that  have  been  given  to  these  reciurent 
questions  for  discussion  ?  I  have  brought  along  a  whole  series 
of  them  ;  it  would  be  of  value  to  know  what  attitude  you  take 
up  towards  some  of  the  statements  that  have  been  made  about 
future  possibihties." 

Einstein  acquiesced,  and  so  I  read  out  a  number  of  ex- 
pressions of  opinion,  given  by  eminent  authorities,  particu- 
larly in  natural  science  and  mathematics.    They  came  under 

ua 


144  EINSTEIN  THE  SEARCHER 

the  heading,  "  The  Future  Revolution  of  Science.*'  At  the 
outset  we  encountered  arguments  by  Bailhaud,  the  director 
of  the  Paris  Observatory  ;  he  dealt  with  the  so-called  "  Problem 
of  Three  Bodies/'  and  with  "  The  Finitude  or  Infinitude  of  the 
Universe." 

Einstein  elucidated  these  questions  as  follows.    The  cele- 
brated Problem  of  Three  Bodies  is  a  special  case  of  the  general 
problem  of  Many  Bodies,  the  object  of  which  is  to  discover  the 
exact  paths  of  the  heavenly  bodies.     If  we  suppose  that  the 
planets  and  the  comets  are  subject  only  to  the  attraction  of 
the  central  body,  the  sun,  then  their  paths  would  be  exactly 
those  given  by  Kepler's  Laws — that  is,  they  would  move  about 
the  central  body,  or,  more  precisely,  about  the  common  centre 
of  gravity  in  perfectly  elliptical  orbits.     The  same  result  would 
happen  if  we  regard  the  orbit  of  a  moon  to  depend  solely  on 
its  parent  planet.     But  this  assumption  is  not  in  agreement 
with  reahty,  since  all  the  bodies  of  our  system  are  also  subject 
to  their  mutual  attraction  depending  on  their  masses  and 
distances.     Consequently  we  have  the  so-called  disturbances, 
perturbations,  and  divergences  from  the  ideal  paths  ;  and  the 
problem    of    ascertaining    these    disturbances    is    essentially 
identical  with  the  Problem  of  Three  Bodies.     Regarded  from 
the  point  of  view  of  pure  mechanics,  this  problem  may  be 
considered  solved  in  so  far  as  we  are  able  to  write  down  the 
equations    of    motion.     But,    in    addition    to    this    purely 
mechanical  process,  there  is  a  mathematical  problem  which 
has  not  been  completely  solved — ^that  is  to  say,  the  integral 
expressions  that  occur  in  it  can  be  calculated  only  approxi- 
mately.    This  makes  no  difference  to  the  practical  calculation, 
since  the  degree  of  approximation,  according  to  the  present 
methods,  may  be  carried  as  far  as  we  wish.     The  error  may 
be  reduced  to  any  desirable  extent,  so  that  it  is  probably  wrong 
to  expect  new  revelations  on  this  point  from  future  upheavals 
in  physics.     We  read  on  and  discovered  that  several  of  the 
scientists  mentioned  did  not  stop  at  expecting  all  advances 
of  the  future  from  pure  theory.     They  had  visions  of  an 
optimum  of  happiness,  to  gain  which  the  increase  of  know- 
ledge alone  did  not  suffice.     Thus  the  celebrated  Swedish  astro- 
physicist Svante  Arrhenius  had  summarized  his  judgment  in 
a  few  lines  :    "  After  the  stupendous  progress  that  has  been 


PROBLEMS  145 

made  in  the  physical  and  chemical  sciences  in  recent  times, 
it  seems  to  me  that  the  moment  has  come  for  attacking  the 
most  important  problems  of  mankind  with  full  success,  namely, 
those  of  biology,  and  in  particular  of  the  art  of  healing,  with 
the  weapons  that  are  furnished  by  the  arsenal  of  the  exact 
sciences."  And  the  mathematician,  Emile  Picard,  Membre 
de  I'Academie,  expressed  himself  in  still  more  hopeful  terms  : 
"  There  is  no  doubt  but  that  the  discoveries  which  the  human 
race  is  awaiting  with  impatience  are  those  that  are  seeking  to 
eliminate  sickness  and  the  decrepitude  of  old  age.  Injections 
giving  immunity  against  all  diseases,  an  elixir  of  life  (une 
eau  de  Jouvence)  for  persons  of  advancing  age — these  are  the 
discoveries  that  are  longed  for  by  every  one.  There  are  also 
sciences  that  are  to  be  termed  '  moral,'  from  which  we  are 
impatiently  expecting  that  guidance  which  will  diminish  the 
hate  which  seems  to  be  increasing  from  day  to  day  among 
the  nations.     That  would  be  a  splendid  discovery." 

"  These  are,  indeed,  noble  and  inspiring  words,"  said  I. 
"  It  shows  how  deeply  rooted  is  the  demand  for  ethical  values 
in  human  nature,  when  even  a  mathematician,  whose  intel- 
lectual interests  are  directed  primarily  towards  exact  results, 
ranks  the  discoveries  of  ethics  above  all  others." 

Einstein  answered :  "  We  must  carefully  distinguish 
between  what  we  wish  for  in  general  and  what  we  have  to 
investigate  as  belonging  to  the  world  of  knowledge.  The 
question  under  consideration  is  not  one  of  wishes  and  feeUngs, 
but  was  unmistakably  aimed  at  the  advances  and  revolutions 
in  the  realm  of  science.  It  does  not  come  within  the  scope 
of  science  at  all  to  make  moral  discoveries !  Its  one  aim  is 
rather  the  Truth.  Ethics  is  a  science  about  moral  values, 
but  not  a  science  to  discover  moral  *  truths.*  Ethics,  conceived 
as  a  science  in  the  usual  way,  can  therefore  serve  to  discover 
or  to  promote  truth  only  indirectly.  To  illustrate  my  point 
of  view  I  shall  quote  an  example  taken  from  a  totally  different 
field  ;  it  is  merely  to  serve  as  an  analogy.  Let  us  consider 
the  game  of  chess.  Its  value  and  its  meaning  is  not  to  be 
sought  in  scientific  factors,  but  in  something  entirely  different, 
in  a  struggle  which  takes  place  according  to  definite  rules. 
But  even  chess,  inasmuch  as  it  sharpens  the  intellect,  may 
exhibit  an  indirect  value  for  promoting  truth.     It  may,  for 

lO 


146  EINSTEIN  THE  SEARCHER 

instance,  suggest  examples  in  permutations,  which  may  con- 
tain mathematical,  that  is,  purely  scientific,  truths.  I  certainly 
do  not  deny  that  there  is  an  ethical  factor  in  all  genuine 
sciences.  For  being  occupied  with  things  for  the  sake  of 
truth  alone  emancipates  and  ennobles  the  mind." 

"  This  ennobhng  effect,'*  I  interposed,  "  should  surely  show 
itself  in  a  moderation  of  the  passions  which  were  mentioned 
in  the  above  expression  of  opinion.  With  Picard  we  should 
expect  above  all  things  to  see  a  diminution  in  the  feehngs  of 
hate  between  peoples,  the  tragic  consequences  of  which  we 
have  experienced." 

Einstein  smiled,  and,  with  a  touch  of  sarcasm,  said,  "  Hate 
is  presumably  a  privilege  of  the  *  cultured,'  who  have  the  time 
and  the  energy  for  it,  and  who  are  not  the  slaves  of  care."  His 
tone  indicated  clearly  that  he  used  the  generic  term  "  cultured  " 
to  denote  the  PhiUstines  of  culture,  its  snobbish  satellites,  but 
not  those  whose  intensive  work  aimed  at  increasing  and 
deepening  the  fields  of  culture.  In  general  he  maintained  his 
view  that  it  is  an  illusion  to  expect  "  discoveries  "  in  the 
realm  of  ethics,  since  every  real  discovery  belonged  alone  to 
the  sphere  of  truth  in  which  the  division  only  into  right  and 
wrong,  not  that  into  good  and  evil,  holds  good. 

This  led  us  to  the  old  question  of  Pilate  :  What  is  Truth  ? 
In  seeking  an  answer  to  this  question  Einstein  first  called 
special  attention  to  the  conception  of  "  approximation," 
which  plays  a  great  part  in  the  actual  search  for  truth,  inas- 
much as  every  physical  truth,  expressed  in  measures  and 
numbers,  always  leaves  some  remainder,  that  marks  its 
distance  from  the  unattainable  truth  of  reality.  This  con- 
ception, which  manifests  itself  so  prominently  in  the  relation 
of  Einstein's  own  researches  to  the  older,  so-called  classical, 
mechanics,  will  be  developed  here  according  to  his  Une 
of  thought  as  far  as  I  can  recollect  from  a  number  of 
conversations. 

Let  us  suppose  that  we  overhear  two  people  arguing  about 
the  shape  of  the  earth's  surface.  The  one  affirms  that  it  is  an 
unhmited  plane,  whilst  the  other  maintains  that  it  is  a  sphere. 
We  should  not  hesitate  a  moment  to  say  that  the  first  is  in  error, 
and  that  the  second  gives  the  true  answer.  As  long  as  the 
question  was  to  be  decided  in  favour  of  a  "  Plane  or  a  Sphere," 


PROBLEMS  147 

the  sphere  would  represent  the  absolute  truth.  Yet  it  would 
be  only  relative,  for  these  two  statements  are  contradictory 
only  between  themselves,  but  will  no  longer  be  so  if  a  third 
assertion  is  made  which  opposes  a  new  alternative  to 
"  sphere." 

If  this  alternative  objection  is  actually  raised,  the  third 
person  would  be  quite  justified  in  saying  that  the  "  sphere  " 
explanation  is  wrong.  For  the  conception  '*  sphere "  re- 
quires that  all  diameters  be  equal,  whereas  we  know  that  they 
are  not  so,  since  the  distance  from  pole  to  pole  has  been  proved 
to  be  smaller  than  that  between  opposite  points  on  the  equator. 
The  earth  is  an  elHpsoid  of  rotation,  and  this  truth  is  absolute 
in  the  face  of  the  errors  which  are  expressed  by  the  terms, 
plane  and  sphere. 

It  would  again  have  to  be  added  that  this  absoluteness 
would  stand  only  as  long  as  this  contradiction  is  regarded  as 
being  one  between  a  definite  sphere  and  a  definite  eUipsoid. 
If,  as  in  the  case  of  the  earth,  there  are  quite  different  diameters 
in  the  equatorial  and  the  diametral  planes,  then  there  is 
complete  contradiction  between  the  two  statements,  and  as 
the  supporter  of  the  eUipsoid  is  right,  the  one  who  supported 
the  sphere  must  now  give  in,  although  he  previously 
triumphed  over  his  first  opponent.  His  statement  was  true 
compared  with  the  latter,  but  showed  itself  to  be  an  error 
when  compared  with  the  statement  of  the  third  person. 

This  does  not  run  coimter  to  the  laws  of  elementary  logic. 
One  of  these,  somewhat  inadequately  called  the  Law  of  Con- 
tradiction, states  that  two  directly  contrary  statements — e.g. 
this  figure  is  a  circle,  and  this  figure  is  not  a  circle — cannot 
both  be  true  simultaneously.  The  truth  of  the  one  implies 
necessarily  the  falseness  of  the  other.  As  this  cannot  be  dis- 
puted, it  follows  in  our  case  that  we  cannot  have  been  con- 
fronted with  contradictory  judgments  at  all  concerning  the 
figure  of  the  earth. 

This  is  to  be  understood  in  a  geometrical  sense.  The 
sphere  does  not  entirely  contradict  the  eUipsoid,  since  it  is  a 
hmiting  case  of  the  latter  :  and  the  plane  is  Ukewise  a  Hmiting 
case  of  the  sphere,  as  weU  as  of  the  surface  of  eUipsoids. 

But  we  are  not  concerned  with  purely  geometrical  con- 
siderations, for  the  earth  is  a  definite  body,  and  not  a  limiting 


148  EINSTEIN  THE  SEARCHER 

configuration  derived  from  abstraction.  We  are  here  dealing 
with  measurable  quantities,  whose  difference  can  be  proved, 
and  hence  we  must  have  one  of  the  disputants  proclaiming  the 
absolute  truth,  whilst  the  other  proclaims  an  absolute  error. 
This,  however,  again  is  incompatible  with  our  result  that 
the  second  person  is  right  in  the  one  case  and  wrong  in  the 
other. 

The  logical  Law  of  Contradiction  overcomes  the  dilemma 
in  the  simplest  way.  None  of  these  assertions  contains  the 
truth,  hence  none  of  these  judgments  allows  the  falseness  of 
the  others  to  be  deduced.  Only  this  may  be  said,  that  there 
is  a  fraction  of  truth  in  each  judgment.  The  true  shape  of  the 
earth  is  given  by  the  plane  to  a  first,  the  sphere  to  a  second, 
the  ellipsoid  of  rotation  to  a  third,  degree  of  approximation  : 
we  reserve  the  right  of  further  approximations,  each  of  which 
in  succession  approaches  a  higher  degree  of  correctness,  but 
none  attains  the  absolute  truth. 

This  reflection  on  a  particular  case  may  be  generaUzed,  and 
remcdns  when  we  extend  it  to  our  attempts  at  grasping  the 
states,  changes,  and  occurrences  of  Nature.  Whenever  we 
talk  of  physical  laws,  we  must  bear  in  mind  that  we  are  deaUng 
with  human  processes  of  thought,  that  are  subjected  to  a 
succession  of  judgments,  courts  of  appeal,  as  it  were,  excluding, 
however,  a  final  court  beyond  which  no  appeal  is  possible. 
Each  new  experience  in  the  course  of  natural  phenomena  may 
render  necessary  a  new  trial  before  a  higher  court,  whose  duty 
is  then  to  give  a  more  definite  or  different  form  to  the  law 
formulated  by  us,  so  as  to  attain  a  still  higher  degree  of 
approximation  to  the  truth. 

If  we  call  to  mind  some  of  the  most  valuable  statements 
made  by  modern  investigators  about  the  nature  of  natural 
laws,  we  recognize  that  they  are  all  connected  by  a  single 
thread  of  thought,  namely,  that  even  in  the  most  certain  law 
there  is  left  a  remainder  that  has  not  been  accounted  for,  and 
that  obHges  us  to  consider  a  greater  approximation  to  the  truth 
as  possible,  even  if  a  final  stage  is  not  attainable. 

Mechanics  furnishes  us  with  the  expression  of  its  laws  in 
equations,  whose  importance  Robert  Kirchhoff  explained  in 
1874  by  a  definition  that  has  been  considered  conclusive  by 
scientists.    According  to  him,  it  is  the  object  of  mechanics  to 


PROBLEMS  149 

describe  completely  (and  not  to  explain)  in  the  simplest  manner 
the  motions  that  occur  in  Nature. 

The  postulate  of  simplicity  is  derived  from  the  fundamental 
view  of  science  as  an  economy  of  thought.  It  expresses  the 
will  of  man's  mind  to  arrive  at  a  maximum  of  result  by  using 
a  minimum  of  effort,  and  to  express  the  greatest  sum  of  experi- 
ence by  using  the  smallest  number  of  symbols.  Let  us  con- 
sider two  simple  examples  quoted  by  Mach.  No  human  brain 
is  capable  of  grasping  all  the  possible  circumstances  of  bodies 
falling  freely,  and  it  may  well  be  doubted  whether  even  a 
supernatural  mind  like  that  imagined  by  Laplace  could  succeed 
in  doing  so.  But  if  we  take  note  of  Galilei's  Law  for  Falling 
Bodies  and  the  value  of  the  acceleration  due  to  gravity,  which 
is  quite  an  easy  matter,  we  are  equipped  for  all  cases,  and  have 
a  compendious  formula,  accessible  to  any  ordinary  mind,  that 
allows  us  to  picture  to  ourselves  all  possible  motions  of  falling 
bodies.  In  the  same  way  no  memory  in  the  world  could  retain 
all  the  different  cases  of  the  refraction  of  hght.  Instead  of 
trying  to  do  the  impossible  task  of  grasping  this  infinite  abund- 
ance, we  simply  take  note  of  the  sine  law,  and  the  indices  of 
refraction  of  the  two  media  in  question ;  this  enables  us  to 
picture  any  possible  case  of  refraction,  or  to  complete  it,  since 
we  are  free  to  reheve  our  memories  entirely  by  having  the 
constants  in  a  book.  Thus  we  have  here  natural  laws  that 
give  us  a  comprehensive  yet  abbreviated  statement  of  facts, 
and  satisfy  the  postulate  of  simpUcity  to  a  high  degree. 

But  these  facts  are  built  up  on  experiences,  and  it  is  not 
impossible  that  some  new  unexpected  experience  wiU  reveal 
a  new  fact,  which  is  not  sufiiciently  taken  into  account  in  the 
law.  This  would  compel  us  to  correct  the  expression  for  the 
law,  and  to  seek  a  closer  approximation  for  the  enlarged 
number  of  facts. 

The  Law  of  Inertia,  according  to  our  human  standard, 
seems  unsurpassable  in  simpHcity  and  completeness  ;  it  seems 
to  us  fundamental.  But  this  law,  which  prescribes  uniform 
rectiUnear  motion  to  a  body  subject  to  no  external  forces, 
selects  only  one  possibiUty  out  of  an  infinite  number  as  being 
valid  for  us.  It  does  not  seem  evident  to  a  child,  and  it  is 
easy  to  imagine  a  good  scholar  in  some  branch  of  knowledge 
other  than  physics,  to  whom  it  would  likewise  not  seem  evident. 


150  EINSTEIN  THE  SEARCHER 

For  it  is  by  no  means  necessary  a  priori  that  a  body  will  move 
at  all  when  all  forces  are  absent.  If  the  law  were  self-evident, 
it  would  not  need  to  have  been  discovered  by  Galilei  in  1638. 
Nevertheless,  it  appears  to  us,  now,  to  be  absolutely  self-evident, 
and  we  can  scarcely  imagine  that  it  can  ever  be  otherwise. 
This  is  simply  because  we  are  bound  to  the  current  set  of  ideas 
that  cannot  extend  beyond  the  sum  of  sense-data  and  experi- 
ences that  have  been  inculcated  into  us  by  heredity  and  en- 
vironment. At  a  very  distant  date  in  the  future  the  average 
mind  may  surpass  that  of  GaHlei  to  the  same  extent  as  GaHlei's 
surpasses  that  of  a  child,  or  of  a  Papuan  native.  And  of  all 
the  infinite  possibilities  one  may  occur  to  a  GaUlei  of  the  distant 
future,  which,  when  formulated  as  a  law,  may  serve  to  describe 
motions  of  a  body  subject  to  no  forces  better  than  the  law  of 
inertia,  proposed  in  1638. 

These  reflections  are  not  mere  hallucinations,  but  have  to 
do  with  scientific  occurrences  that  we  have  observed  in  the 
twentieth  century.  Newton's  equation  that  gives  the  Law  of 
Attraction  is  beyond  doubt  a  model  of  simplicity,  and  it  would 
have  occurred  to  no  thinking  person  of  even  the  last  generation 

to  doubt  its  accuracy.     The  easily  grasped  expression  k — ^ 

apparently  expresses  truth  in  a  law  which  is  valid  for  all 
eternity.  In  this  expression,  he  denotes  a  gravitational  con- 
stant, that  is,  a  quantity  which  is  invariable  in  the  whole  uni- 
verse ;  m  and  m}  are  two  masses  that  act  attractively  on  one 
another  ;  and  r  is  the  distance  between  them.  But  Newton 
has  been  followed  by  Einstein,  who  has  proved  that  this  ex- 
pression represents  only  an  approximate  value,  that  leaves  a 
small  remainder  as  an  error  that  may  be  detected  if  the  greatest 
refinement  be  made  in  our  methods  of  observation.  The 
equations  that  have  been  set  up  by  Einstein  represent  the 
approximation  that  is  to  be  considered  final  for  the  present, 
and  that  may  remain  valid  for  thousands  of  years.  They  are 
certainly  very  complicated,  being  included  in  a  system  of 
differential  equations  of  awe-inspiring  length,  and  we  may 
feel  tempted  to  object  with  the  question :  how  do  they  agree 
with  Kirchhoff' s  postulate  that  the  simplest  description  of  the 
motions  must  be  sought  ?  But  this  objection  falls  to  the 
ground  if  we  look  carefully  into  the  question.     For  simplicity 


PROBLEMS  151 

consists  not  merely  in  being  brief  or  in  excluding  difficulty 
from  a  formula,  but  rather  in  asserting  the  simplest  relation 
to  the  universe  as  a  whole,  which  is  independent  of  all  systems 
of  reference.  When  this  independence  is  proved — and  in 
Einstein's  case  it  is  so — the  compUcated  aspect  of  the  formula 
disappears  entirely  in  the  Ught  of  the  higher  simplicity  and 
unity  of  the  world-system  that  presents  itself — a  world-system 
that  is  directed  in  conformity  with  the  one  fundamental  law  of 
general  relativity  as  well  in  the  motion  of  the  electrons  as  in 
motion  of  the  most  distant  stars.  With  regard  to  the  other 
postulate,  that  of  completeness,  i.e.  absolute  accuracy,  we 
have  been  furnished  with  proofs  that  have  rightly  excited  the 
wonder  of  the  present  generation.  But  are  we  then  to  recognize 
the  Principle  of  Approximation  in  every  direction  ?  Is  there 
then  nothing  that  can  be  proved  rigorously,  nothing  that  is 
unconditionally  valid  in  the  form  of  knowledge  that  corresponds 
exactly  to  truth  ? 

We  are  led  to  think  of  mathematical  theorems,  which, 
when  they  have  once  been  proved,  are  evident  to  the  same 
degree  as  the  axioms  from  which  they  have  been  derived,  by 
virtue  of  logic  which  cannot  be  disputed  since  a  contradiction 
leads  to  absurdity.  It  has  been  said  that  mathematics  est 
scientia  eorum,  qui  per  se  clara  sunt,  that  is,  is  the  science  of 
what  is  self-evident. 

But  here  again  doubts  arise.  If  we  should  get  to  know 
only  a  single  case,  in  which  the  self-evident  came  to  grief,  the 
road  to  further  doubts  becomes  open.  Such  a  case  will  now 
be  quoted. 

As  we  know,  a  tangent  is  a  straight  Une,  which  makes 
contact  with  a  curve  at  two  coincident  (or  infinitely  near) 
points  without  actually  cutting  the  ciurve.  The  simplest  case 
of  this  is  the  perpendicular  at  the  extremity  of  a  radius  of  a 
circle.  And  it  agrees  fuUy  with  what  our  feehng  leads  us  to 
expect  when  it  is  stated  that  every  curved  Hne  that  is  "  con- 
tinuous,*' that  is,  which  discloses  no  break  and  no  sudden  bend, 
has  a  tangent  at  every  point.  Analysis,  which  treats  plane 
curves  as  equations  in  two  variables,  gives  the  direction  of  the 
tangent  in  terms  of  the  differential  coefficient,  and  declares 
accordingly  that  every  continuous  function  has  a  differential 
coefficient,  that  is,  may  be  differentiated,  at  every  point.     The 


152  EINSTEIN  THE  SEARCHER 

one  statement  amounts  to  the  same  as  the  other,  since  there 
must  be  an  equivalent  graphical  picture  corresponding  to  every 
functional  expression. 

But  this  apparently  rudimentary  theorem  involves  an 
error,  which  was  not  discovered  before  the  year  1875.  The 
theory  of  curves  has  been  in  existence  for  centuries,  but  it 
occurred  to  no  one  to  doubt  the  general  vahdity  of  this  theorem 
of  tangents.  It  was  regarded  as  self-evident,  as  a  mathe- 
matical intuition.  And  certainly  neither  Newton,  nor  Leibniz, 
nor  Bernoulli,  not  to  mention  the  mathematicians  of  olden 
times,  even  dreamed  that  a  continuous  curve  without  a  tangent, 
or  a  continuous  function  without  a  differential  coefficient, 
was  possible. 

-1:  Moreover,  a  proof  of  the  theorem  had  been  accepted.  It 
appeared  in  text-books,  and  was  often  to  be  heard  in  lecture 
rooms  ;  nor  was  a  shadow  of  a  doubt  suggested.  For  it  was 
not  merely  a  demonstratio  ad  oculos,  but  it  appeared  directly 
to  our  sense  of  intuition.  And  we  may  safely  say  that  up  to 
the  present  day  no  one  has  ever  been  able  to  imagine  a  con- 
tinuously curved  line  which  has  no  tangent ;  no  one  has  been 
able  to  picture  even  one  point  of  such  a  curve  at  which  no 
tangent  could  be  drawn. 

Nevertheless,  scientists  appeared  who  began  to  entertain 
doubts.  In  the  case  of  Riemann  and  Schwarz  these  doubts 
assumed  a  concrete  form,  in  that  they  proved  that  certain 
functions  are  refractory  at  certain  points.  But  Weierstrass 
was  the  first  to  make  a  real  breach  in  the  old  belief  that  was  so 
firmly  rooted.  He  set  up  a  function  that  is  continuous  at  every 
point,  but  differentiable  at  no  point.  The  graphical  picture 
would  thus  have  to  be  a  continuous  curve  having  no  tangent 
at  all. 

What  is  the  appearance  of  such  a  configuration  ?  We  do 
not  know,  nor  shall  we  presumably  ever  get  to  know.  During 
a  conversation  in  which  this  problem  of  Weierstrass  arose, 
Einstein  said  that  such  a  curve  lay  beyond  the  power  of 
imagination.  It  must  be  remarked  that,  although  the  mathe- 
matical expression  of  the  Weierstrass  function  is  not  exactly 
simple,  it  is  not  inordinately  complex.  Moreover,  seeing  that 
one  such  function  (or  curve)  exists,  others  will  soon  be  added 
to  it  (Poincare  mentions  that  Darboux  actually  gave  other 


PROBLEMS  153 

examples  even  in  the  same  year  that  the  first  was  discovered) ; 
there  will,  indeed,  be  found  an  infinite  number  of  them.  We 
may  go  still  further,  and  say  that,  corresponding  to  each  curve 
that  has  tangents,  there  are  an  infinite  number  that  have 
no  tangents,  so  that  the  former  form  the  exception  and  not  the 
rule.  This  is  an  overwhelming  confession  that  shakes  the 
foundations  of  our  mathematical  convictions,  yet  there  is  no 
escape. 

How  may  we  apply  the  principle  of  "  approximation  "to 
these  considerations  ?  May  we  say  that  the  theorem  that  was 
believed  earlier  is  an  approximation  to  a  mathematical  truth  ? 

This  is  possible  only  conditionally,  in  a  certain  extremely 
limited  sense,  namely,  if  we  picture  to  ourselves  that  point 
in  the  development  of  science  at  which  the  conception  and 
properties  of  tangents  first  began  to  be  investigated.  Com- 
pared with  this  stage  of  science,  the  above  theorem  denotes  a 
first  approximation  to  the  truth,  in  spite  of  its  incorrectness ; 
for  it  makes  us  acquainted  with  a  great  abundance  of  curves 
that  are  very  important  for  us  and  that  exhibit  tangents  at 
every  point.  This  knowledge  brings  us  a  step  nearer  to  the 
more  approximate  truth  given  by  Weierstrass*s  example. 
In  the  distant  future,  the  earnest  student  will  learn  this  theorem 
only  as  a  curious  anecdote,  just  as  we  hear  of  certain  astro- 
logical and  alchemistic  fallacies.  He  will  learn,  in  addition, 
other  theorems  that  are  looked  on  as  proved  by  us  of  the  present 
day,  although  actually  they  were  proved  only  approximately. 
For  what  does  it  mean  when  Gauss,  for  example,  repudiated 
certain  proofs  of  earlier  algebraists  as  being  "  not  sufficiently 
rigorous,'*  and  replaced  them  by  more  rigorous  proofs  ?  It 
signifies  no  more  than  that,  in  mathematics,  too,  what  appears 
to  one  investigator  as  flawless,  strict,  and  evident,  is  found  by 
another  to  have  gaps  and  weaknesses.  Absolute  correctness 
belongs  only  to  identities,  tautologies,  that  are  absolutely  true 
in  themselves,  but  cannot  bear  fruit.  Thus  at  the  foundation 
of  every  theorem  and  of  every  proof  there  is  an  incommensurable 
element  of  dogma,  and  in  all  of  them  taken  together  there 
is  the  dogma  of  infallibility  that  can  never  be  proved  nor 
disproved. 

It  must  appear  extremely  interesting  that,  at  first  sight, 
this   example   of  the  tangent  has  its  equivalent  in  Nature 


154  EINSTEIN  THE  SEARCHER 

herself,  namely,  in  molecular  motions  the  investigation  of 
which  is  again  largely  due  to  Einstein. 

Jean  Perrin,  the  author  of  the  famous  book,  Atoms,  describes, 
in  the  introduction,  the  connexion  between  this  mysterious 
mathematical  fact  and  results  that  are  visible  and  may  be 
shown  by  experiment,  to  which  we  have  been  led  by  the  study 
of  certain  milky-looking  (colloidal)  liquids. 

If,  for  example,  we  look  at  one  of  those  white  flakes,  which 
we  get  by  mixing  soap  solution  with  common  salt,  we  at  first 
see  its  surface  sharply  outUned,  but  the  nearer  we  approach 
to  it,  the  more  indistinct  the  outline  becomes.  The  eye 
gradually  finds  it  impossible  to  draw  a  tangent  to  a  point  of 
the  surface  ;  a  straight  line  which,  viewed  superficially,  seems 
to  run  tangentially,  is  found  on  closer  examination  to  be 
oblique  or  even  perpendicular  to  the  surface.  No  microscope 
succeeds  in  dispelUng  this  uncertainty.  On  the  contrary, 
whenever  the  magnification  is  increased,  new  unevennesses 
seem  to  appear,  and  we  never  succeed  in  arriving  at  a  continuous 
picture.  Such  a  flake  furnishes  us  with  a  model  for  the  general 
conception  of  a  function  which  has  no  differential  coefiicient. 
When,  with  the  help  of  the  microscope,  we  observe  the  so- 
called  Brownian  movement,  which  is  molecular  by  nature, 
we  have  a  parallel  to  the  curve  which  has  no  tangent,  and 
the  observer  is  left  only  with  the  idea  of  a  function  devoid 
of  a  differential  coefficient.  .  .  .  We  find  ourselves  obliged, 
ultimately,  to  give  up  the  hope  of  discovering  homogeneity 
at  all  in  studying  matter.  The  farther  we  penetrate  into  its 
secrets,  the  more  we  see  that  it,  matter,  is  spongy  by  nature 
and  infinitely  complex  ;  all  indications  tend  to  show  that  closer 
examination  will  reveal  only  more  discontinuities. 

I  have  not  yet  had  an  opportunity  of  seeing  these  Brownian 
movements  under  the  microscope,  but  I  must  mention  that 
Einstein  has  repeatedly  spoken  to  me  of  them  with  great 
enthusiasm,  of  an  objective  kind,  as  it  were,  for  he  betrayed 
neither  by  word  nor  by  look  that  he  himself  has  done  research 
leading  to  definite  laws  that  have  a  recognized  place  in  the 
history  of  molecular  theory. 

As  soon  as  we  approach  the  question  of  molecular  ir- 
regularities we  recognize  that,  when  we  earlier  spoke  of  the 
figure  of  the  earth  in  discussing  the  principle  of  "  appro xima- 


PROBLEMS  155 

tion,"  we  were  still  very  far  from  the  limit  that  may  be 
imagined.  We  had  set  up  the  three  stages  :  plane — sphere — 
eUipsoid  of  revolution,  as  relative  geometrical  steps,  beyond 
which  there  must  be  still  further  geometrical  approximations. 
If  we  imagine  all  differences  of  level  due  to  mountains  and 
valleys  to  be  eliminated,  for  example,  and  if  we  suppose  the 
earth's  surface  to  consist  entirely  of  liquid,  undisturbed  by  the 
shghtest  breath  of  wind,  even  then,  the  ellipsoid  is  by  no  means 
the  final  description.  For  now  the  discontinuities  from  mole- 
cule to  molecule  begin,  the  infinite  number  of  configurations 
without  tangents,  the  macroscopic  parallels  of  what  the  white 
flake  soap  solution  showed  as  microscopically,  and  no  conceiv- 
able geometry  would  ever  be  adequate  to  grasp  these  pheno- 
mena. We  arrive  at  a  never-to-be-completed  list  of  functions 
which  can  never  be  described  either  in  words  or  in  symbolic 
expressions  of  analysis. 

But  even  if  the  ultimate  geometrical  truth  is  hidden  behind 
the  veils  of  Maya,*  we  are  yet  left  with  the  consolation  that  the 
method  of  approximation,  even  when  appUed  to  a  relatively 
modest  degree,  produces  remarkable  results  in  the  realm  of 
numbers.  Let  us  consider  for  a  moment  in  the  simple  figure 
of  a  circle  the  ratio  between  the  circumference  and  the  radius. 

As  we  know,  this  ratio  is  constant,  and  is  called  in  honour 
of  the  man  who  first  gave  a  trustworthy  value  for  it,  Ludolf's 
number,  namely,  tt  (pi).  Thus  it  makes  no  difference  whether 
we  consider  a  circle  as  small  as  a  wedding-ring,  or  as  large  as 
a  circus  arena,  or  even  one  the  radius  of  which  is  as  great  as 
the  distance  of  Sirius.  And  it  makes  just  as  little  difference 
what  happens  to  the  circle  whilst  it  is  being  measured  ;  the 
above  ratio  must  remain  constant. 

But  here,  too,  a  contradiction  makes  itself  heard,  issuing 
from  one  section  of  modem  science.  It  calls  to  mind  the 
saying  of  Dove  that  when  professors  are  not  quite  sure  about 
a  thing  they  always  preface  their  remarks  with  the  phrase  : 
*4t  is  well  known  that"  .  .  .  We  should  be  well  advised  in 
avoiding  this  method  of  expression  altogether,  for  even  when 
we  feel  quite  sure,  the  ghost  of  the  unknown  lurks  behind 
what  we  fain  would  call  well  known. 

The  theorem  that  all  circles  without  exception  are  subject 

*  Maya = appearance. 


156  EINSTEIN  THE  SEARCHER 

to  the  same  measure-relation  belongs  a  priori  to  the  synthetic 
judgments.  But  fields  of  thought  have  been  discovered  in 
which  the  a  priori  has  lost  its  power.  Mathematics — once 
a  quintessence  of  synthetic  statements  a  priori  —  is  now 
regarded  as  being  dependent  on  physical  conditions.  Physical 
conditions,  however,  are  empirical  and  subject  to  change. 
Therefore,  since  the  a  priori  is  not  subject  to  change,  we 
encounter  a  discrepancy.  It  leads  to  the  question  :  Is  the 
Euclidean  geometry  with  which  we  are  familiar  the  only 
possible  geometry  ?  Or,  in  particular  :  Is  it  the  only  possible 
measure-relation  ? 

Einstein  replies  in  the  negative.  He  not  only  shows  how 
another  geometry  is  possible,  but  he  also  discloses  what  once 
seemed  inconceivable,  namely,  that  if  we  wish  to  describe 
the  course  of  the  phenomena  of  Nature  exactly  by  means  of 
the  simplest  laws,  it  is  not  only  impossible  to  do  so  with  the 
help  of  Euclidean  geometry  alone,  but  that  we  have  to  use  a 
different  geometry  at  every  point  of  the  world,  dependent 
on  the  physical  condition  at  that  point. 

From  the  comparatively  simple  example  of  two  systems 
rotating  relatively  to  one  another,  Einstein  shows  that  the 
peripheral  measurement  of  a  rotating  circle,  as  viewed  from 
the  other  system,  exhibits  a  peculiarity  which  does  not 
accompany  the  radial  measurement.  Fot,  according  to  the 
theory  of  relativity,  the  length  of  a  measuring  rod  is  to  be 
regarded  as  being  dependent  on  its  orientation.  In  the  case 
quoted,  the  rod  undergoes  a  relative  contraction  only  when 
applied  along  the  circumference,  so  that  we  count  more  steps 
than  when  we  measure  the  circumference  of  the  same  circle 
at  rest,  that  is,  in  non-rotation.  Since  the  radius  remains 
constant  in  each  case,  we  ^'dt  a  relatively  greater  value  for  tt, 
which  shows  that  we  are  no  longer  using  Euclidean  geometry. 

Yet,  formerly,  before  such  considerations  could  even 
be  conceived  in  dreams,  this  tt  was  regarded  as  absolutely 
established  and  immutable  ;  and  observers  used  every  possible 
means  of  determining  its  value  as  accurately  as  possible. 

In  Byzantium  there  Uved  during  the  eleventh  and  twelfth 
centuries  a  learned  scholar,  Michael  Psellus,  whose  fame  as 
the  "  Foremost  of  Philosophers  *'  stretched  far  and  wide, 
and  whose  mathematical  researches  were  regarded  as  worthy 


PROBLEMS  157 

of  great  admiration.  This  grand  master  had  discovered  by 
analytical  and  synthetical  means  that  a  circle  is  to  be  regarded 
as  the  geometric  mean  between  the  circumscribed  and  the 
inscribed  square,  which  gives  to  the  above  quantity,  as  may 
easily  be  calculated,  the  value  \/8,  that  is,  2*8284271.  .  .  . 
In  other  words,  the  length  of  the  circumference  is  not  even 
three  times  that  of  the  radius. 

We  have  the  choice  of  regarding  the  result  of  Psellus  as 
an  approximation,  or  as  mere  nonsense.  Every  schoolboy 
who,  in  a  spirit  of  fun,  measures  a  circular  object,  say  a  top, 
with  a  piece  of  string,  arrives  at  a  better  result,  but  the  con- 
temporaries of  Psellus  accepted  this  entirely  wrong  figure 
with  credulous  reverence,  and  continued  to  birni  incense  at 
the  feet  of  the  famous  master.  It  is  all  very  well  for  us  of 
the  present  to  call  him  a  donkey.  We  have  just  as  much 
right  in  saying  that  mathematicians  differ,  not  in  their  natures, 
but  only  in  the  order  of  their  brain  functions.  If  a  man  hke 
Psellus  missed  the  mark  by  so  much,  it  is  possible  that  men 
Hke  Fermat  or  Lagrange  may  also  have  erred  occasionally 
or  even  consistently. 

No  heavenly  power  wiU  give  us  a  definite  assurance  to 
the  contrary,  and  all  of  us  may  be  just  as  false  in  our  judgment 
of  accepted  celebrities  as  were  the  Byzantines  eight  hundred 
years  ago  in  their  estimate  of  PseUus. 

Whereas  the  latter  had  obtained  a  value  "  less  than  3,'* 
there  are  learned  documents  of  about  the  same  date  that  have 
been  preserved,  according  to  which  the  value  of  ir  comes  out 
as  exactly  4.  Compared  with  this  grandiose  bunghng,  even 
the  observations  mentioned  in  the  Old  Testament  are  models 
of  refinement.  For,  as  early  as  three  thousand  years  ago, 
it  is  stated  of  the  mighty  basin  in  the  temple  of  Solomon 
(First  Book  of  Kings,  chapter  vii.) :  "  And  he  made  a  molten 
sea,  ten  cubits  from  the  one  brim  to  the  other  :  it  was  round 
all  about,  and  his  height  was  five  cubits  ;  and  a  fine  of  thirty 
cubits  did  compass  it  round  about."  Thus  ir  here  appears 
as  3,  an  approximation  which  no  longer  satisfied  later  genera- 
tions. The  wise  men  of  the  Talmud  went  a  step  further, 
in  saying  3  plus  a  little  more  ;  and  this  agrees  roughly  with 
the  actual  value. 

The  view  became  more  and  more  deeply  rooted  that  this 


158  EINSTEIN  THE  SEARCHER 

TT  was  |a  main  pillar  of  mathematical  thought  and  calculation. 
The  more  the  problem  of  the  quadrature  of  the  circle  seized 
on  men's  minds,  the  greater  were  the  efforts  made  to  find 
the  exact  value  of  this  "  httle  more  "  of  the  Talmud.  Since 
1770  we  know  that  this  is  not  possible,  for  ir  is  not  rational, 
that  is,  it  can  be  represented  only  as  an  infinite  and  irregular 
(that  is,  non-repeating)  decimal  expression.  It  occupies, 
further,  a  special  rank  as  a  transcendental  quantity ;  this 
fact  was  proved  by  Lindemann  as  late  as  1882  for  the  first 
time.  Yet,  even  nowadays,  there  are  incorrigible  devotees 
of  quadrature,  who  are  still  hunting  a  solution  because  they 
cannot  rid  themselves  of  the  hallucination  that  such  a  simple 
figure  as  the  circle  must  submit  ultimately  to  a  constructive 
process. 

The  correct  way  was  to  carry  out  an  even  more  accurate 
determination  of  the  decimal  figures.  The  above-mentioned 
Ludolf  van  Ceulen  got  as  far  as  the  35th  place  of  decimals  ; 
at  the  turn  of  the  eighteenth  century  the  looth  decimal 
place  was  reached.  Since  1844,  thanks  to  the  lightning 
calculator  Dase,  we  have  its  value  to  the  200th  decimal  place, 
and  this  should  satisfy  even  the  most  extravagant  demands. 
This  number,  associated  with  the  circle,  is  a  classical  example 
of  how  an  approximation  that  is  expressible  in  figures  of  very 
small  value  gives  an  order  of  accuracy  that  can  be  described 
only  by  using  fantastic  illustrations. 

If  we  take  a  circle  of  the  size  of  the  equator,  and  also 
multiply  the  value  of  the  diameter  of  the  earth  by  tt,  we  know 
that  the  latter  result  will  not  be  exactly  equal  to  the  former, 
and  that  there  will  always  be  a  small  remainder.  If  this 
discrepancy  were  less  than  a  metre,  the  order  of  exactness 
would  be  extraordinarily  high,  for  a  metre  is  practically 
insignificant  compared  with  a  mighty  circle  of  the  dimensions 
of  the  earth's  circumference. 

Let  us  stipulate  still  greater  accuracy.  We  demand  that 
the  error  is  to  be  less  than  the  thickness  of  the  thinnest  human 
hair.  We  find,  then,  that  we  must  take  for  tt  at  most  15 
places  of  decimals.  Thus,  if  we  use  7^  =  3*14159265358973, 
we  are  applying  a  means  of  calculation  that  reduces  the 
possible  error  in  all  measurements  of  circles  on  the  earth 
to  a  degree  beyond  the  Umits  of  human  perception. 


PROBLEMS  159 

If  we  pass  beyond  the  world  out  into  celestial  space,  and 
consider  circles  of  the  dimensions  of  a  planetary  orbit,  nay, 
further,  if  we  pass  on  to  the  Milky  Way  or  even  to  the  limit  of 
visible  stars,  to  find  space  for  our  circle,  and  if  in  this  case  we 
still  reduce  the  discrepancy  so  as  to  be  less  than  any  length 
that  is  observable  under  a  microscope,  then  the  last  given 
value  of  TT  still  suf&ces.  Yet  we  must  not  forget  the  proviso  : 
semper  aliquid  haeret,  something  unsolved  still  chngs  to  the 
problem. 

Such  numerical  approximations,  however  instructive  they 
may  be,  nevertheless  retain  a  comparatively  playful  character, 
and  furnish  only  a  superficial  analogy  to  the  most  important 
approximations  that  are  contained  in  our  natural  laws  them- 
selves. It  is  these,  above  all,  that  manifest  themselves  so 
clearly  in  Einstein's  Ufe-work,  and  they  bear  the  same  relation 
to  the  former  as  truth  bears  to  correctness.  Truth  comprises 
the  greatest  conceivable  circle  of  ideas  and  passes  far  beyond 
the  sphere  of  correctness,  which  deals  only  with  measure- 
relations,  and  not  with  the  things  in  themselves.  If  Einstein, 
as  we  learn,  emphatically  declares  truth  to  be  the  only  object 
of  science,  he  means  the  strictly  objective  truth  that  is  to  be 
derived  from  Nature,  the  true  relationship  of  phenomena  and 
occurrences,  independently  of  whether  restless  philosophy 
assigns  a  question  mark  to  this  ultimate  objectivity.  A  great 
discoverer  in  the  realm  of  Nature  cannot  and  dare  not  proceed 
otherwise.  For  him  there  is  behind  the  veil  of  Maya  not  a 
phantom  that  finally  vanishes,  but  something  knowable,  that 
becomes  ever  clearer  and  more  real  as  he  detaches  each  suc- 
cessive veil  in  his  process  of  approximation. 

During  this  conversation,  when  we  were  talking  of  the 
"  Future  of  the  Sciences,"  Einstein  gave  his  ideas  free  rein, 
shooting  far  ahead  of  the  views  and  prognostications  of  the 
above-mentioned  scientists  : 

"  Hitherto  we  have  regarded  physical  laws  only  from  the 
point  of  view  of  Causality,  inasmuch  as  we  always  start  from 
a  condition  known  at  a  definite  cross-section  of  time,  that  is, 
by  taking  a  time-section  of  phenomena  in  the  universe,  as,  for 
example,  a  section  corresponding  to  the  present  moment.  But, 
I  beheve,"  he  added,  with  earnest  emphasis,  "  that  the  laws  of 
Nature,  the  processes  of  Nature,  exhibit  a  much  higher  degree 


160  EINSTEIN  THE  SEARCHER 

of  uniformity  of  connexion  than  is  contained  in  our  time- 
causality  !  This  possibiHty  suggests  itself  to  me  particularly 
as  the  result  of  certain  reflections  concerning  Planck's  Quantum 
Theory.  The  following  may  be  conceived :  What  belongs  to 
a  definite  cross-section  of  time  may  in  itself  be  entirely  devoid 
of  structure,  that  is,  it  might  contain  everything  that  is  physi- 
cally conceivable,  even  such  things  (so  I  understood  him  to  say) 
as,  in  our  ordinary  physical  thought,  we  consider  impossible 
of  realization,  for  example,  electrons  of  arbitrary  size,  and 
having  an  arbitrary  charge,  iron  of  any  specific  gravity,  etc. 
By  our  causality  we  have  adjusted  our  thought  to  a  lower 
order  of  structural  Umitations  than  seems  realized  in  Nature. 
Real  Nature  is  much  more  limited  than  our  laws  imply.  To 
use  an  allegory,  if  we  regard  Nature  as  a  poem,  we  are  Hke 
children  who  discover  the  rhyme  but  not  the  prosody  and  the 
rhythm."  I  interpret  this  as  meaning  that  children  do  not 
suspect  the  restrictions  to  which  the  form  of  the  poem  is 
subject,  and  just  as  Uttle  do  we,  with  our  causality,  divine 
the  restrictions  which  Nature  imposes  on  occurrences  and 
conditions  even  when  we  regard  them  as  governed  by  the 
natural  laws  we  have  found. 

Thus  a  leading  problem  of  science  in  the  future  will  be 
to  discover  the  restrictions  of  Nature  as  compared  with  the 
apparent  causality  implied  in  physical  laws. 

We  have  in  this  an  example  of  the  transcendental  per- 
spectives that  are  opened  up  when  we  accompany  Einstein 
on  one  of  his  excursions  of  thought.  In  this  case  it  is  actually 
a  question  of  ultimate  things,  of  a  region  of  discovery  of 
which  we  cannot  yet  form  a  conception,  and  it  appears 
doubtful  whether  the  problems  latent  in  it  are  to  be  treated  by 
making  investigations  into  physical  nature,  or  whether  they 
are  to  be  allotted  to  speculative  philosophy. 

In  the  first  place,  Einstein's  remark  seems  to  aim  at  nothing 
less  than  a  revision  of  the  conception  of  causaUty.  However 
much  has  been  done  to  purify  this  conception  and  to  make  it 
clear,  we  have  here,  perhaps,  a  new  possibility  of  refining  it 
by  making  a  synthesis  of  scientific  and  abstract  philosophical 
views.  We  shall  just  touch  very  lightly  and  superficially  on 
the  possibility  of  a  synthesis  giving  us  an  avenue  to  truth. 
Whoever  has  heard  these  words  of  Einstein,  feels  the  need  of 


PROBLEMS  161 

getting  on  to  firm  ground  to  rescue  himself  out  of  the  turmoil 
of  ideas  into  which  he  has  been  plunged. 

What  is  Causality  ?  A  physiological  answer  may  be  given 
by  saying  that  it  is  the  irrepressible  animal  instinct,  rooted 
in  our  brain-cells,  that  compels  us  to  connect  together  things 
that  we  have  experienced  and  imagined.  Poets  have  defined 
Hunger  and  Love  as  the  fimdamental  elements  of  our  social 
fives  ;  we  need  only  add  the  thirst  for  causafity  to  this  to 
complete  the  fist  of  primary  instincts.  For  this  mental  thirst 
is  not  less  intense  than  our  bodily  hunger,  and  is  even  greater 
in  that  it  never  forsakes  us  for  a  moment.  It  is  easier  for  the 
body  to  check  breathing  than  for  the  soul  to  still  the  question 
of  the  why  and  wherefore,  of  the  cause  and  effect,  of  the  ante- 
cedent and  consequent. 

This  ceaseless  search  for  a  connexion  between  occurrences 
has  become  organized  into  a  fixed  and  immovable  form  of 
thought,  which  remains  mysterious  even  when  we  imagine 
that  we  have  efiminated  all  the  mystery  from  it.  The  rela- 
tions that  we  seek  and  that  we  regard  as  being  of  an  elementary 
character  are  totally  foreign  to  Nature  herself.  David  Hume, 
the  first  real,  and  at  the  same  time  the  most  penetrating, 
explorer  into  this  form  of  thought,  said  that,  in  the  whole  of 
Nature  not  a  single  case  of  connexion  is  disclosed  which  we 
are  able  to  grasp.  All  happenings  appear,  in  reafity,  dis- 
connected and  separate.  One  "  follows  on  "  another,  but  we 
can  never  detect  a  connexion  between  them.  They  appear 
**  co-joined,"  but  never  "  connected."  And  since  we  can  form 
no  idea  of  what  has  never  presented  itself  to  our  outer  or  inner 
perception,  the  necessary  conclusion  seems  to  be  that  we  have 
absolutely  no  idea  of  causal  connexions  or  causative  forces, 
and  that  these  expressions  are  quite  devoid  of  meaning,  how- 
ever much  they  may  be  used  in  philosophical  discussions  or 
in  ordinary  fife.  This  **  Inquiry  concerning  Human  Under- 
standing," with  its  atmosphere  of  resignation,  has  been  ela- 
borated in  manifold  ways,  particularly  by  Kant  and  the 
Kantians  ;  for  it  is  impossible  to  take  up  a  philosophic  thread 
without  entering  on  an  examination  of  the  fundamental 
question  concerning  the  existence  of  a  causafity  which  fies 
outside  our  instinct  for  causafity.  It  is  also  inevitable  that, 
whenever  we  start  out  in  this  direction,  we  encounter  the 
II 


162  EINSTEIN  THE  SEARCHER 

further  question :  What  is  Time  ?  For  causality  directs 
itself  to  the  problem  of  succession,  both  of  sensations  and 
phenomena,  consequently  the  two  questions  are  not  only 
intimately  connected,  but  are  really  only  different  expressions 
of  one  and  the  same  question.  Time,  which  according  to 
Descartes  and  Spinoza  is  a  modus  cogitandi,  not  an  affectio 
rerum,  and,  according  to  Kant,  is  an  a  priori  form  of  thought, 
dominates  our  intelhgence  with  the  same  sovereign  power,  as 
the  imagined  course  of  things  :  what  we  perceive  in  the  corre- 
sponding act  of  thought  is  regarded  as  temporal  and  causal, 
and  impossible  of  further  analysis. 

Now,  the  conception  of  time  has  been  entirely  revolu- 
tionized by  Einstein  himself;  and  it  may  be  expected  that 
the  conception  of  causality,  too — which,  in  accordance  with 
custom,  we  still  endow  with  a  separate  existence — will  also  be 
affected  by  this  revolution. 

We  thus  approach  a  relativization  of  causality,  and  we 
may  advance  a  step  further  in  this  direction,  if  we  call  to  mind 
the  differences  of  time-perception  that  Nature  herself  leaves 
open  to  us.  It  must  be  clearly  understood  that  we  are  not 
dealing  at  present  with  the  theoretical  time  of  physics,  in 
the  sense  of  Einstein's  theory,  but  with  something  physio- 
logical that  ultimately,  however,  resolves  itself  into  a  rela- 
tivization of  time,  and  hence  also  of  the  causal  connexions  in 
time. 

To  do  this,  we  have  to  follow  the  lines  of  reasoning  de- 
veloped by  the  celebrated  St.  Petersburg  academician,  K.  E. 
von  Baer,  and  we  need  extend  it  only  very  Httle  to  get  at 
the  heart  of  causality,  if  we  start  from  his  address  of  i860  : 
"  Which  View  of  Living  Nature  is  correct  ?  "  For  the  human 
brain  is  a  part  of  living  nature,  and  hence  the  processes  of 
thought  may  also  be  conceived  as  expressions  of  life. 

The  starting-point  is  a  figment,  the  fictitious  character 
of  which  vanishes  as  soon  as  we  approach  its  results.  The 
bridge  of  thought  may  be  destroyed  later  ;  it  suffices  to  carry 
us  temporarily,  as  long  a3  it  lands  us  in  safety  on  the  other 
side. 

The  rapidity  of  perception,  of  the  arbitrary  motions,  of 
intellectual  life  seems  in  the  case  of  various  animals  to  be 
proportional  approximately  to  the  rapidity  of  their  pulse- 


PROBLEMS  163 

beats.  Since,  for  example,  the  pulse  of  a  rabbit  beats  four 
times  as  quickly  as  that  of  a  bull,  it  will,  in  the  same  interval 
of  time,  also  perceive  four  times  as  quickly,  and  will  be  able 
to  execute  four  times  as  many  acts  of  will,  and  will  experience 
four  times  as  much  as  the  bull.  In  the  same  astronomical 
length  of  time  the  inner  Hfe  and  perceptual  world,  in  the  case 
of  various  animals,  including  Man,  will  take  place  at  different 
specific  rates,  and  it  is  on  these  rates  that  each  of  these  living 
creatures  bases  its  subjective  measure  of  time.  Only  when 
compared  with  our  own  measure  of  time  does  an  organic 
individual,  say,  a  plant,  appear  as  something  permanent  in 
size  and  shape,  at  least  within  a  short  interval.  For  we  may 
look  at  it  a  hundred  times  and  more  in  a  minute,  and  yet 
notice  no  external  change  in  it.  Now,  if  we  suppose  the 
pulse-beat,  the  rate  of  perception,  the  external  course  of  Hfe, 
and  the  mental  process  of  Man,  very  considerably  accelerated 
or  retarded,  the  state  of  affairs  becomes  greatly  changed, 
and  phenomena  then  occur,  which  we,  fettered  by  our 
physiological  structure,  should  have  to  reject  as  being  fantastic 
and  supernatural,  although,  on  the  supposition  of  a  new 
structure  they  would  be  quite  logical  and  necessary.  If  we 
suppose  human  Hfe  from  childhood  to  old  age  to  be  compressed 
into  a  thousandth  part  of  its  present  duration,  say,  into  a 
month,  so  that  the  pulse  beats  a  thousand  times  more  quickly 
than  occurs  in  our  own  experience,  we  should  be  able  to  follow 
the  course  of  a  discharged  bullet  very  exactly  from  point  to 
point  with  our  eyes,  more  easily  than  we  can  at  present  observe 
the  fHght  of  a  butterfly.  For  now  the  motion  of  the  bullet 
in  a  second  will  be  distributed  among  at  least  looo  pulse- 
beats,  and  wiU  induce  at  least  looo  perceptions,  and  accord- 
ingly, in  comparison  with  our  everyday  perception,  it  will 
appear  looo  times  slower.  If  the  duration  of  our  Hfe  were 
again  to  be  reduced  to  a  thousandth  of  its  first  reduced  value, 
that  is,  shortened  to  about  forty  minutes,  then  our  flowers 
and  herbs  would  seem  just  as  motionless  and  immutable  as 
rocks  and  mountains,  in  which  we  only  infer  the  changes 
without  having  directly  observed  them.  We  would  in  the 
course  of  our  Hves  see  little  more  of  the  growth  and  decay  of 
a  bud  and  a  flower  in  full  bloom  than  we  at  present  see  of 
the  geological  changes  in   the  earth's   crust.     The   acts  of 


164  EINSTEIN  THE  SEARCHER 

animals  would  be  much  too  slow  to  be  seen  ;  at  most,  we 
could  infer  them  as  we  do  the  motions  of  the  stars  at  present. 
If  life  were  shortened  still  further  in  the  same  way,  light 
would  cease  to  be  an  optical  occurrence  to  us.  Instead  of 
seeing  the  things  on  which  light  falls,  we  should  become 
aware  of  them  as  being  audible,  and  what  we  at  present  call 
tones  and  noises  would  long  have  ceased  to  have  an  effect 
on  the  ear. 

If,  however,  we  let  our  fancy  roam  in  the  opposite  direction, 
that  is,  if,  instead  of  compressing  the  duration  of  human 
life,  we  expand  it  enormously,  what  a  different  picture  of 
the  world  would  present  itself  !  If,  for  example,  the  pulse- 
beat,  and  hence  the  rate  of  perception,  were  to  be  made  a 
thousand  times  slower,  so  that  the  average  human  life  would 
be  spread  out  over,  say,  80,000  years,  and  that  we  should 
experience  in  one  whole  year  only  as  much  as  we  now  ex- 
perience in  a  third  of  a  day,  then,  in  every  four  hours  winter 
or  any  other  season  would  pass  by,  vegetation  would  spring 
up  and  as  rapidly  die.  Many  a  growth  would  not  be  per- 
ceptible, on  account  of  its  relative  rapidity  compared  with 
the  rate  of  the  pulse-beat.  For  example,  a  mushroom  would 
suddenly  come  into  existence,  like  a  newly  formed  spring. 
Day  and  night  would  alternate  as  a  light  and  a  dark  minute  ; 
and  the  sun  would  appear  to  fly  over  the  heavens  like  a  fiery 
projectile.  If  we  were  again  to  make  the  duration  of  human 
life  a  thousand  times  longer  still,  and  hence  the  rate  of  life 
a  thousand  times  slower  still,  we  should,  during  the  whole  of 
an  ordinary  year,  be  able  to  have  only  190  distinct  perceptions, 
so  that  the  difference  between  day  and  night  would  vanish 
entirely,  and  the  sun's  path  woiild  be  a  glowing  circular 
band  in  the  heavens,  and  all  changes  of  form  that  seem  to  us 
to  happen  quietly  and  regularly,  and  to  preserve  a  certain 
permanency,  would  melt  together  in  the  wild  stream  of 
happening,  engulfed  in  its  onward  rush. 

Are  we  justified  in  opposing  to  this  relative  perception 
of  time  "  our  own  "  time,  which  is  something  specific  and 
dependent  on  our  constitution  as  human  beings  ?  Should 
we  not  rather  adopt  the  view  that  this  specific  time,  adapted 
to  our  particular  pulse-beat,  gives  only  a  very  limited  picture 
of  the  world,  which  is  conditioned  and  determined  by  the 


PROBLEMS  165 

limitations  of  our  own  dej&nite  intelligence  ?     Is  it,  perhaps, 
only  a  distorted  picture,  a  caricature,  of  actual  occurrences  ? 

An  intelligence  infinitely  superior  to  our  own  would  no 
longer  be  dependent  on  the  separate  sensations  such  as  are 
presented  to  us  with  the  rhythm  of  the  pulse.  For  such  a 
mind  there  would  be  no  metronomic  foundation  in  the  sequence 
of  occurrences,  beyond  what  represents  itself  as  time  to  our 
understanding.  He  would  be  situated  outside  of  time  in  what 
Thomas  Aquinas  called  the  nunc  stans,  in  the  stationary 
present,  without  a  retrospect  of  the  past  and  without  ex- 
pectation of  a  future.  Without  the  Before  and  the  After,  the 
occurrences  of  the  world  would  acquire  the  clearest  and 
simplest  meaning,  hke  that  given  by  an  equation  of  identity. 
What  presents  itself  to  us  as  a  "  succession  "  of  events  would 
merge  together  into  one  whole,  just  as  a  succession  of  numerical 
calculations  become  summarized  in  a  rule  of  calculation,  or 
as  a  series  of  logical  operations  resolves  into  a  logical  self- 
evident  truth.  If  the  mind  conceived  by  Laplace  actually 
existed,  it  would  stand  above  the  necessity  of  introducing 
time  as  a  quantity  into  its  world-equations,  for  time  is  a 
purely  anthropomorphic  quantity,  produced  by  our  percep- 
tion, and  regulated  by  our  own  characteristic  pulses.  Accord- 
ingly, the  conception  of  causality,  too,  which  is  indissolubly 
connected  with  time,  must  be  regarded  as  anthropomorphic, 
as  something  that  we  read  into,  and  not  out  of.  Nature.  We 
should  at  least  have  to  recognize  that  if  there  is  a  causality 
outside  ourselves,  then  we  can  learn  only  a  minimum  about 
it,  and  even  this  only  in  a  world  displaced  or  distorted  by 
the  accidental  rate  of  our  pulse-beat. 

Let  us  now  repeat  Einstein's  assertion  "  that  the  laws  of 
Nature,  the  processes  of  Nature,  exhibit  a  much  higher  degree 
of  uniformity  of  connexion  than  is  contained  in  our  time- 
causaUty  !  It  is  possible  that  what  belongs  to  a  definite 
cross-section  of  time  may  in  itself  be  entirely  devoid  of  struc- 
ture, that  is,  it  might  contain  ever5d:hing  that  is  physically 
conceivable,  even  such  things  as,  in  our  ordinary  physical 
thought,  we  consider  impossible  of  reaUzation,  for  example, 
iron  of  any  arbitrary  specific  gravity."  It  seems  to  me  that 
the  non-physicist  will,  perhaps,  gain  a  clearer  insight  into  these 
highly  significant  words  of  Einstein,  now  that  he  has  received 


,166  EINSTEIN  THE  SEARCHER 

the  assistance  of  these  physiological  considerations.  It  must 
be  granted  that  the  philosophic  grounds  of  Einstein  are  quite 
different  and  lie  much  deeper  than  those  of  von  Baer,  who 
starts  from  organic  functions  and  ends  by  arriving  at  a 
mysterious  relativity  that  is  yet  consistent  in  itself.  Never- 
theless, there  is  one  point  of  contact,  inasmuch  as  in  each  case 
possibilities  that  lie  apparently  extra  naturam  are  suggested. 

Einstein  says  :  '  *  Hitherto  we  have  regarded  physical  laws 
only  from  the  point  of  view  of  causality,  inasmuch  as  we  always 
start  from  a  condition  known  at  a  definite  cross-section  of 
time,  as,  for  example,  a  section  corresponding  to  the  present 
moment.*'  At  our  own  risk  an  easy  paraphrase  of  his  words 
will  be  attempted : 

The  time-section  of  the  present  contains  for  us  the  sum 
of  all  previous  experiences,  out  of  which  the  necessary  course 
of  our  thought  sifts  out  the  category  of  causaUty. 

What  is  not  present  in  experience  cannot  appear  in  our 
causality.  Let  us  consider  for  a  moment  Hume's  example  of 
the  Indian  who  has  never  known  ice.  Without  being  told, 
and  if  he  is  dependent  only  on  his  own  sensations,  he  would 
never  learn  that  water  freezes  in  cold  climates.  The  influence 
of  cold  on  water  is  not  gradual,  corresponding  to  an  increase 
of  cold,  and  not  one  that  may  be  anticipated  in  all  its  conse- 
quences, but  at  the  freezing-point  water,  which  a  moment 
before  was  a  very  mobile  liquid,  passes  into  a  very  rigid  solid. 
The  causality  of  the  Indian  cannot  account  for  this.  If  we 
tell  him  of  this  phenomenon,  he  has  two  courses  open  to  him. 
Either  he  refuses  to  believe  it — and  this  would  be  quite 
natural,  since  rigid  water  is  to  him  as  meaningless  as  is  a  square 
circle  to  us.  Or  else  he  beheves  the  story,  and  then  his  Hst 
of  categories  incurs  a  break,  passing  through  the  middle  of 
causality.  He  has  then  to  reconcile  himself  to  the  assumption 
that  something  that  is  meaningless  to  him  and  that  stands  out- 
side the  connexion  of  cause  and  effect  is  possible  of  reaUzation. 
Up  to  that  moment,  in  his  time-section  of  the  present,  there 
was  no  room  for  it  in  his  causaUty.  To  Torricelli  the  concep- 
tion of  liquid  air,  which  we  have  been  able  to  prepare  only 
since  1883,  would  have  appeared  impossible  and  incompatible 
with  his  causaUty. 

So  there  is  no  room  in  our  causaUty  for  the  idea  of  iron 


PROBLEMS  167 

with  the  specific  gravity  of  air,  or  with  one  several  times  that  of 
gold.  For,  reasoning  along  the  lines  of  our  causaUty,  we  shoiild 
conclude  that  a  substance  that  is  so  light  or  so  heavy  may, 
indeed,  exhibit  chemical  relationship  with  iron,  but  it  would 
not  itself  be  sufficiently  defined  by  the  term  iron. 

Now  Einstein  also  said :  "  Real  Nature  is  much  more 
limited  (or  bound)  than  our  laws  imply."  A  sceptic  might  be 
disposed  to  take  these  statements  separately  in  order  to  con- 
strue a  contradiction  out  of  them.  For,  if  there  are  limiting 
conditions  in  Nature,  which  are  foreign  to  the  views  expressed 
in  our  laws,  how  would  it  then  be  possible  for  phenomena, 
which  cannot  be  imagined,  to  become  reahzed  ?  If  Nature 
can  do  this,  surely  she  must  have  more  Hberty  than  we  seek 
to  impose  on  her.  This  apparent  contradiction  vanishes  if 
we  treat  the  conception  of  structural  design  or  uniformity  as 
something  distinct  from  the  measure  of  all  experience  up  to 
the  present.     This  would  give  us  the  following  interpretation  : 

Out  of  the  manifold  of  occurrences  that  are  possible  in 
mechanical  Nature,  real  Nature  selects  a  very  closely  defined 
manifold.  Thus  the  true  laws  imply  a  much  greater  degree  of 
hmitation  than  those  known  to  us.  For  example,  the  laws 
known  to  us  at  present  would  not  be  affected  if  we  should  dis- 
cover electrons  of  arbitrary  size  or  iron  of  arbitrary  specific 
weight.  But  Nature  reahzes  only  electrons  of  a  quite  definite 
size  and  iron  of  a  definite  specific  weight. 

Let  us  bear  in  mind  that  in  aiming  at  ultimate  truths  we 
have  no  final  courts  of  appeal.  Nor  are  the  latter  to  be 
assumed  even  when,  in  pursuing  a  theory,  we  encounter  a 
difficulty,  which  at  first  exhibits  all  the  signs  of  a  direct  con- 
ceptual contradiction.  It  should  rather  be  reahzed  that  a 
fiction  containing  an  initial  but  only  provisional  contradiction 
serves  as  a  starting-point  for  just  those  investigations  that  are 
most  subtle  and  that  have  far-reaching  consequences.  We 
should  have  no  Infinitesimal  Calculus,  no  Algebra,  no  Atomic 
Theory,  no  Theory  of  Gravitation  if,  to  avoid  all  initial  con- 
tradictions, we  surrender  the  fiction  of  differentials,  of  imaginary 
quantities,  of  the  atom,  of  action  at  a  distance.  In  short, 
it  may,  indeed,  be  said  that  not  only  knowledge,  but  also  hfe, 
the  holding  together  of  people  by  convention,  law,  and  duty, 


168  EINSTEIN  THE  SEARCHER 

would  become  impossible  if  we  did  not  accept  the  fiction 
of  free  will,  which  directly  contradicts  the  determinate  char- 
acter of  all  happening,  including  actions  and  motives,  which, 
physically,  alone  seems  recognizable. 

Fiction  (not  to  be  confused  with  hypothesis)  and  anthropo- 
morphism, in  spite  of  their  inner  inconsistency,  are  the  two 
poles  about  which  our  thoughts  and  our  hves  revolve.  And 
no  doctrine  will  ever  soar  to  such  heights  that  it  will  be  able 
to  deny  completely  its  origin  from  these  roots  of  all  thought. 
The  Archimedean  thought-centre  of  the  universe,  which  would 
enable  us  to  hft  the  world  out  of  its  hinges,  is  unattainable, 
because  it  does  not  exist  at  all. 

Is  this  also  to  apply  to  the  new  physics,  whose  results  are 
to  be  regarded  as  the  last  word  in  scientific  knowledge  ?  Many 
a  hypercritical  thinker  might  be  led  away  by  the  current  of 
the  preceding  statement,  and  feel  disposed  to  answer  in  the 
afiirmative,  were  it  not  that,  here  too,  a  contradiction  intrudes 
itself.  This  is  expressed  in  the  fact  that  not  one  of  the  present- 
day  philosophers  is  in  a  position  to  pursue  the  threads  of  this 
theoretical  fabric  to  their  hidden  ends. 

Thus  we  arrive  at  a  parting  of  the  ways.  Whoever  aims 
at  becoming  thoroughly  famihar  with  Einstein's  new  world- 
system  finds  that  the  study  of  the  theory  claims  so  much 
attention  that  there  is  scarcely  a  possibility  left  of  proceeding 
to  an  ultimate  philosophical  analysis.  And  whoever  is  ab- 
sorbed only  by  the  desire  of  making  philosophic  investiga- 
tions soon  enough  arrives  at  border-hnes  of  thought,  at  which 
his  conscience  warns  him  to  beware  of  insufiicient  scientific 
knowledge.  He  will  be  attacked  by  doubts  as  to  whether  he 
has  properly  understood  the  theory.  And  he  will  be  con- 
fronted with  the  question  whether  he  is  justified  in  drawing 
ultimate  philosophical  conclusions  before  he  has  mastered  all 
the  mathematical  details. 

As  far  as  can  be  judged  at  present,  only  one  thinker  has, 
so  far,  had  sufiiciently  wide  knowledge  to  enable  him  to  corre- 
late the  physical  theory  methodically  with  the  theory  of  know- 
ledge. I  mean  Professor  Moritz  Schlick  of  Rostock,  who  has 
set  out  his  ideas  systematically  in  his  book  Erkenntnislehre, 
which  is  extraordinary  in  itself  and  in  its  great  scope  ;  it 
takes  us  beyond  Kant.     In  Schhck's  opinion  Einstein's  theory 


PROBLEMS  169 

furnishes  us  with  the  key  to  new  and  unexpected  chambers  of 
thought  ;  it  is  a  wonderful  instrument  for  opening  up  new 
avenues,  and  would  appear  more  wonderful  still  if  we  could 
use  this  instrument  without  having  recourse  to  anthropo- 
morphism. This  Hmitation  may  lead  to  a  Utopia,  or  may  en- 
tail a  circulus  vitiosus.  But  we  have  one  philosophy  nowadays 
which  apphes  to  what  cannot  be  fulfilled  **  AS  if  "  it  really 
is  capable  of  fulfilment.  Among  the  disciples  of  Vaihinger,  the 
founder  of  the  As-If-doctrine  of  thought,  we,  however,  notice 
the  tendency  to  follow  anthropomorphic  and  fictitious  paths 
also  in  his  field  of  thought. 

From  numerous  utterances  of  Einstein,  I  have  gathered 
that  he  himself  does  not  give  his  unquaHfied  approval  to  all 
attempts  at  unraveUing  the  ultimate  problems  by  means  of 
philosophy,  that  is,  by  using  metaphysics  alone.  He  does  not 
deprecate  these  endeavours,  but  even  expresses  admiration 
for  some  of  the  newer  works,  as  for  that  of  Schhck,  yet  he  sees 
certain  obstacles  in  the  purely  philosophical  methods,  that  at 
least  restrain  him  from  taking  a  systematic  interest  in  them. 
This  reluctant  acceptance  of,  and  doubt  in,  the  processes  of 
philosophy,  that  has  never  forsaken  the  exact  investigator, 
this  suspicious  attitude  which  scents  traces  of  sophistic  and 
scholastic  machinations  in  all  metaphysical  arguments,  also 
asserts  itself  in  him  in  a  noticeable  form.  He  feels  the  absence 
of  rigour  and  of  consistency  of  direction,  which  is  a  guarantee 
of  progress  in  passing  from  one  result  to  another,  in  the  method 
of  thought  of  those  who  are  pure  philosophers  :  and  he  de- 
plores the  spongy  and  murky  appearance  of  certain  ex- 
pressions of  thought,  which,  it  must  be  admitted,  form  a  poor 
contrast  to  the  completeness  and  the  crystal  clearness  of 
mathematico-physical  reasoning.  There  was  an  inscription 
on  the  portals  of  the  Athenian  Academy  which  stated  that 
entrance  was  forbidden  to  all  who  had  had  no  mathematical 
training  ;  we  may  imagine  next  to  it  an  academy  of  pure 
transcendental  philosophy,  bearing  the  inscription  :  No  exact 
research  allowed  !  I  beUeve  that  this  clear-cut  distinction 
would  tally  with  Einstein's  view. 

In  the  case  of  the  great  Ernst  Mach,  for  whom  Einstein 
has  intense  admiration,  we  observe  a  similar  attitude,  or  we 
may  say  that,  in  the  language  of  allegory,  he  sang  openly  the 


170  EINSTEIN  THE  SEARCHER  v 

same  refrain  in  another  key.  He  never  ceased  reiterating  that 
he  was  properly  "  no  philosopher  at  all,  but  only  an  investigator 
of  Nature."  At  the  beginning  of  the  introduction  to  one  of 
his  works  we  read  his  confession  :  "  Without  in  the  slightest 
degree  being  a  philosopher,  or  even  wishing  to  be  one  .  .  ."  ; 
and  some  lin^es  further  on  he  calls  himself  sarcastically  "  a 
mere  amateur  sportsman "  in  philosophical  regions.  Yet, 
Mach's  initial  remark  is  followed  by  a  remarkable  result,  for 
the  book  in  question,  Knowledge  and  Error  (Erkenntnis  und 
Irrtum),  is  to  be  reckoned  among  the  most  important  works 
in  philosophical  literature ;  and  he  himself,  the  amateur 
sportsman,  who  did  not  even  desire  to  be  called  a  philosopher, 
accepted  in  1895  the  post  of  Professor  of  Philosophy  at  Vienna 
University.  It  was  merely  his  timidity  in  the  face  of  the 
philosophical  fraternity  that  had  made  him  emphasize  re- 
peatedly the  distinction  between  his  own  work  and  that  of  the 
philosophers,  whereas  in  his  heart  he  had  nourished  a  passion 
for  Philosophy,  the  first  mother  of  Science.  And  in  my 
opinion  such  a  moment  may  arrive  for  even  the  most  rigorous 
investigator  when  he  succumbs  to  the  siren  strains  from 
the  shores  of  philosophy. 

As  far  as  Einstein  himself  is  concerned,  I  cannot  venture 
on  a  prognostication.  Even  though  he  belongs  to  the  category 
and  rank  of  Descartes,  Pascal,  d'Alembert,  and  Leibniz,  in 
whom  Mathematics  and  speculative  Philosophy  are  inter- 
mingled, he  is  yet  characterized  by  such  a  pronounced  in- 
dividuality, that  it  is  quite  inadmissible  to  draw  conclusions 
about  him  from  others.  He  has  no  need  to  experience  a  day 
of  Damascus,  for  he  carries  the  gospel  of  salvation  in  himself, 
and  it  radiates  from  him.  One  thing  seems  possible,  in  my 
opinion,  namely,  that  Einstein  will  occasionally  roam  into  the 
neighbouring  realm  merely  from  aesthetic  motives.  Although 
the  means  of  philosophy  are  nebulous  and  more  indefinite 
than  those  of  exact  science,  which  are  almost  glaringly  distinct, 
philosophy  itself  for  this  reason  is  the  more  closely  related  to 
Art.  And  a  theory  that  applies  to  the  whole  universe  must 
assuredly  contain  many  germs  that  may  come  to  life  if  sub- 
jected to  the  methods  of  Art.  The  connecting  link  between 
Kant  and  Schiller  shows  in  what  sense  this  is  to  be  understood. 
Even  at  present  there  are  indications  in  Art  which  tend  to 


PROBLEMS  171 

show  that  it  is  ready  to  estabhsh  points  of  contact  with 
Knowledge.  In  France  symphonic  poems  were  written  on 
the  measure  relations  of  the  circle,  and  on  logarithms  :  these 
are  at  present  only  curiosities,  but  may  in  future  become 
models.  At  a  much  later  date,  perhaps,  the  four-dimensional 
universe  may  become  ripe  for  treatment  by  such  methods  of 
Art.  On  the  way  to  this  goal  there  is  the  treatment  with  the 
symbolic,  non-rigorous,  and  semi-poetic  means  of  expression 
used  by  Philosophy.  Many  will  use  their  efforts  to  achieve 
this,  and  perhaps  they  will  come  within  closer  range  of  success, 
if  Einstein  himself  lends  a  helping  hand.  It  will  not  be 
possible  to  arrive  at  new  physical  truths  by  following  this 
path,  but  those  that  are  actually  known  will  be  traced  more 
readily  to  the  great  mainstream  of  philosophy.  To  fathom  the 
secrets  of  the  world  is  the  work  of  a  recluse,  but  to  make  it 
comprehensible  to  a  wide  circle,  a  preacher  is  necessary,  who 
uses  the  beautiful  methods  of  philosophical  rhetoric.  GDsmos 
denotes  the  World  and  its  Ornamentation ;  its  creator. 
Demiurge,  is  a  master  who  fashions  his  forms  along  the  Hnes 
of  Art. 

Thus  we  have  learned  what  Einstein  regards  as  the  sole 
purpose  of  Science,  namely,  the  search  after  Truth.  For  him, 
the  latter  is  something  absolute  in  itself,  and  the  possibihty 
of  getting  nearer  to  it  is  as  great  as  the  impossibihty  of  de- 
riving results  of  scientific  use  from,  say,  ethical  discoveries. 
For  ethics  is  a  field  which  is  haunted  by  the  conceptual 
ghosts,  and  the  manner  of  treatment,  ordine  geometrico,  that 
Spinoza  wished  to  apply  to  it,  is  reserved  for  physics.  Einstein 
leaves  the  inverse  philosophical  query  :  "Is  not  Truth  in 
itself  only  something  that  we  have  constructed  in  imagina- 
tion ?  "  to  those  who  find  pleasure  in  sauntering  along  paths 
of  thought  that  are  totally  unconnected,  whereas  he  himself 
advances  in  a  straight  hne  with  the  consciousness  that  even 
if  the  goal  is  unattainable,  he  will  at  least  not  lose  the  right 
direction  ! 


CHAPTER   VIII 
HIGHWAYS  AND  BY-WAYS 

Practical  Aims  of  Science. — Pure  Search  for  Truth. — Retrospective  Con- 
siderations.— The  Practical  Side  of  Kepler. — A  Saying  of  Kant. — Mathe- 
matics as  a  Criterion  of  Truth. — Deductive  and  Inductive  Methods. — Con- 
ceptual and  Perceptual  Knowledge. — Happiness  and  the  Pleasures  of  Theory. 
— Achievements  of  Science  and  Works  [of  Art. — Ethical  Results. — Minor 
Questions. 

I 

AGAIN  we  chanced  to  refer  to  the  great  subject :   Can 
or   should   theoretical   science   also   pursue   practical 
aims  ? 
It  is  impossible  to  overrate  the  importance  of  this  question. 
It  haunts  us  daily  and  often  enough  looms  up  threateningly 
on  the  horizon  of  mankind.     Observe  what  form  the  discus- 
sions of  educated  people  take  when  the  finest  and  most  sub- 
lime achievements  of  mind  are  being  debated  :    one  talks  of 
the  wonders  of  research  in  the  remotest  corners  of  astronomy 
where  the  structures  of  world-wide  star-systems  are  being 
investigated  ;    we  hear  observations  about  the  theories  that 
aim  at  tracing  the  cosmogonic  development  of  universes  from 
the  original  chaos  of  countless  ages  ago.     We  hear  mention 
of  exalted  sciences,  the  Theory  of  Functions  and  Numbers, 
whose  founders  and  representatives  are  just  as  remarkable 
in  propounding  problems  as  in  solving  them,  and  inevitably 
the  following  question  obtrudes  itself :    Of  what  use  is  it, 
ultimately  ?     What  can  one  do  with  it  ?     Can  it  be  admitted 
that  theoretical  science  has  an  object  of  its  own,  or  have  we 
at  least  the  right  to  maintain  the  hope  that,  sooner  or  later,  it 
will  bring  us  a  real  "  Utility  "  expressible  in  practical  terms  ? 
And  just  as  the  devotees  of  pure  art  have  framed  the 
expression,  "  L'art  pour  I'art,"  so   Einstein   proclaims   that 
science  is  its  own  object,  "  Science  for  its  own  sake  !  "     It 
carries  its  aims  absolutely  in  itself  and  must  not,  through  aim- 

172 


HIGHWAYS  AND  BY-WAYS  173 

ing  at  other  purposes,  stray  from  its  own  highways.  "It  is 
my  inner  conviction,"  said  he,  "  that  the  development  of 
science  itself  seeks  in  the  main  to  satisfy  the  longing  for  pure 
knowledge,  which,  psychologically,  asserts  itself  as  religious 
feehng." 

"  To  yourself.  Professor,  the  practical  aspect  seems  com- 
paratively insignificant  ?  " 

"  I  did  not  say  that,  and  it  was  not  imphed  in  the  question. 
We  must  not  lose  sight  of  our  premises.  As  long  as  I  am  in- 
terested in  working  along  Hues  of  research — this  was  the 
assumption — the  practical  aspect,  that  is,  every  practical 
result  that  is  found  simultaneously  or  arises  out  of  it  later, 
is  a  matter  of  complete  indifference  to  me." 

Far  be  it  from  me,  even  in  thought,  to  wish  to  question  this 
confession  of  faith,  particularly  as  the  fact  that  it  comes  from  a 
searcher  of  the  truth  gives  it  the  more  weight.  Yet  a  certain 
uneasiness  has  crept  over  me  because  voices  have  recently 
made  themselves  heard  that  demand  for  science  a  totally 
different  tendency.  They  arise  not  only  from  the  pubhc  at 
large,  but 'also  from  academic  circles.  Just  a  short  time  ago 
I  read  an  exposition  by  a  well-known  scientist,  W.  Wien, 
in  which  he  indulged  in  a  violent  polemic  against  the  view 
that  purely  scientific  objects  are  alone  vaHd.  Professor  Wien 
addressed  himself  particularly  to  German  physicists,  reproach- 
ing them  with  underestimating  technical  science,  and  with 
regarding  it  as  a  "  lowering  of  status  "  when  a  physicist  enters 
into  practical  Hfe. 

To  this  Einstein  remarked  :  "  I  do  not  know  at  whom  this 
reproach  is  aimed,  but  I  venture  to  think  that  my  own  atti- 
tude can  never  have  given  rise  to  an  attack  of  this  Idnd.  For  I 
make  no  divisions  of  rank,  and  recognize  no  higher  and  no 
lower  status.  I  affirm  only  what  is  the  nature  of  science 
herself,  and  the  objects  according  to  which  she,  objectively, 
has  to  direct  her  gaze.  Whatever  further  orientation  in- 
dividual investigators  may  seek  for  themselves  depends  on 
the  determining  conditions  of  life  of  each,  although  these 
conditions  do  not  serve  as  a  means  for  deducing  the  main 
lines  of  research.  The  accusation  that  I  am  unwarranted  in 
putting  forward  this  view  will,  I  hope,  not  be  levelled  at  me, 
for  my  connexions  with  practice  are  manifold  enough,  and  up 


174  EINSTEIN  THE  SEARCHER 

to  the  present  moment  I  have  often  collaborated  with  practical 
physicists.  ..." 

'*  As  I  have  regretfully  observed  when  you  were  obliged 
to  interrupt  a  conversation  with  me  to  give  an  audience  to 
impatient  persons  seeking  advice  in  technical  matters  !  " 

"  My  own  associations  with  the  world  of  practice  are  not, 
indeed,  of  recent  date.  My  own  parents  originally  wanted  me 
to  become  a  technical  scientist,  and  I  was  expected  to  choose 
this  profession  to  earn  my  Hvelihood.  I  was  not,  however, 
sympathetically  inclined  to  it,  for  even  at  an  early  age  these 
practical  aims  were  to  me,  on  the  whole,  indifferent  and  de- 
pressing. My  idea  of  human  culture  did  not  coincide  with 
the  current  view,  that  cultural  development  is  to  be  measured 
in  terms  of  technical  progress.  Doubts,  indeed,  arose  in  me 
as  to  whether  technical  improvements  and  advances  would 
actually  contribute  to  the  well-being  of  mankind.  I  must  add 
that,  later,  when  I  came  into  actual  touch  with  technical 
science,  my  opinion  became  somewhat  modified,  for  the  reason 
that,  here  too,  pleasures  of  theory  often  visited  me." 

The  true  position  is  probably  that  the  technical  worker 
who  does  not  merely  think  out  improvements  for  machines, 
but  occupies  himself  with  inventions  on  a  higher  plane,  never 
ceases  to  feel  himself  a  theorist,  since  his  achievements  are 
dependent  for  their  inspiration  on  the  fruits  of  theory.  The 
practical  results  of  to-day  are  rooted  in  the  theoretical  results 
of  decades  ago,  and  what  is  nowadays  regarded  as  an  idea  of 
pure  research  may  in  later  decades  acquire  practical  value. 
Whether  it  actually  becomes  of  value,  or  not,  is  of  httle  account 
in  judging  the  idea.  At  any  rate  experience  has  shown  that 
the  beginning  of  theoretical  investigations  hardly  ever  gives 
us  the  chance  of  making  prognostications.  We  spoke  of  the 
discoveries  of  Volta,  Ampere,  and  Faraday.  When  these 
were  first  known,  the  world  might  have  asked  :  Why  have 
they  been  disclosed  ?  To  what  can  they  be  applied  ?  Of  what 
use  are  they  ?  Nowadays  we  know  the  answers  that  still 
lay  hidden  at  that  time,  and  we  proudly  point  to  modern 
dynamos.  But  does  a  dynamo  really  represent  the  significance 
of  these  discoveries  ?  Would  the  importance  and  rank  of 
Volta,  Ampere,  and  Faraday  be  less  if  the  dynamo  had  not 
come  into  existence  ?     Only  an  out-and-out  materiaHst  would 


HIGHWAYS  AND  BY-WAYS  175 

affirm  this,  and,  strictly  speaking,  the  question  should  not 
even  be  raised.  For  it  is  in  a  sense  equivalent  to  wishing  to 
judge  of  the  importance  and  significance  of  the  Polar  Star 
from  its  usefulness  to  the  navigator  on  the  earth's  surface  in 
finding  his  bearings.  We  may  put  the  question  (although  only 
in  the  spirit  of  psychological  curiosity,  and  without  expect- 
ing much  elucidation)  :  Would  these  discoverers  have  been 
particularly  happy  if  they  had  divined  the  far-reaching  conse- 
quences of  their  work  ?  Did  they,  indeed,  in  the  course  of  their 
abstract  researches,  have  a  pre-vision  of  the  future  dominated 
by  the  dynamo  ?  Einstein  refused  to  answer  this  in  the 
decisive  negative.  He  left  room,  if  ever  so  little,  for  doubts — 
that  is,  he  considered  that,  in  all  probabihty,  these  three  dis- 
coverers had  no  presentiment  of  these  consequences,  and  even 
if  they  had  in  a  dream  caught  a  gUmpse  of  our  present  electrical 
age,  their  zest  for  discovery,  their  "  pleasure  in  theory,"  could 
scarcely  have  been  increased  ;  for  they  were  discoverers  by 
nature,  who,  swept  along  by  their  own  spirits,  did  not  need  to 
wait  to  satisfy  the  desires  of  practical  application. 

In  Einstein's  opinion,  the  presentiment  that  a  discovery 
may  have  practical  appHcations  in  the  future  may  react  on 
pure  research.  He  quoted  bacteriology  as  a  proof  of  this. 
In  the  series  of  eminent  bacteriologists,  ranging  from  Spallan- 
zani  to  Schwann  and  Pasteur,  there  were  certainly  some 
whose  desire  for  knowledge  was  directed  primarily  towards 
discovering  purely  scientific  relationships.  Pcisteur  himself 
started  from  the  theoretical  question  of  the  creation  of  life,  that 
is,  from  the  problem  of  the  origin  of  organic  creatures  from  in- 
organic matter  without  the  medium  of  parent  organisms.  As  a 
pan-spermist  he  took  up  a  negative  attitude,  that  is,  he  tried 
to  prove  that  it  is  impossible  to  discover  a  bridge  between 
organic  and  inorganic  matter.  Yet  he  doubtless  knew  that 
his  theoretical  efforts  stretched  out  into  practical  regions,  and 
he  may  easily  have  foreseen  that  they  would  exert  a  very 
important  influence  on  Medicine  and  Hygiene,  although  he 
could  not  measure  its  full  extent.  In  this  case,  then,  we  cannot 
fail  to  recognize  that  a  certain  connexion  between  the  desire 
for  pure  knowledge  and  the  impulse  to  apply  it  practically 
is  possible,  serviceable,  and  justified  in  itself. 

An  influence  in  the  opposite  direction  is  also  possible,  and 


176  EINSTEIN  THE  SEARCHER 

when,  during  the  course  of  our  conversation,  we  went  in  search 
of  examples,  we  came  across  one  of  great  interest.  It  shows  us 
that  a  question  may  arise  out  of  ordinary  practice  that  may 
open  up  an  immense  field  of  pure  knowledge,  nay,  it  may  lead 
to  a  science  of  very  wide  scope.  As  this  example  is  not  well 
known,  I  shall  mention  it  here  ;  I  do  so  with  additional 
pleasure  as  the  scientist  involved  is  one  of  those  whom  Einstein 
quotes  most  frequently  and  for  whom  he  has  the  greatest 
admiration,  namely,  Johannes  Kepler.  First  we  have  the 
surprising  fact  that  Kepler,  who,  even  when  at  the  height  of 
his  fame,  was  not  free  from  care,  was  once  the  possessor  of  some 
money.  In  the  year  1615,  his  blessed  year  of  fortune,  the  great 
astronomer  owned  a  comfortable  home  in  Linz,  and  even  dared 
to  conceive  the  idea  of  placing  some  well-filled  casks  in  his 
cellar;  nay,  more,  he  was  in  a  position  to  publish  a  new  scientific 
work  at  his  own  expense,  and  thus  appear  as  his  own  publisher. 
This  production  of  Kepler  and  his  casks  of  wine  are  directly 
connected,  as  we  see  clearly  from  the  title  :  Doliometrie, 
literally,  "  The  Measurement  of  Casks."  But  the  title  of 
the  work  gives  not  the  slightest  hint  of  its  importance.  For 
these  investigations  relating  to  wine-casks  actually  became 
the  foundation  of  a  science  of  sovereign  power,  the  In- 
finitesimal Calculus. 

What  was  Kepler's  aim  ?  It  was  something  entirely 
practical,  and  directed  to  a  definite  purpose,  quite  independent 
of  "  pleasures  of  theory,"  to  repeat  Einstein's  expression. 
His  problem  was  a  question  of  economy,  of  using  material 
sparingly  and  appropriately,  in  accordance  with  the  require- 
ments of  the  careful  head  of  a  house.  How  must  such  a 
cask  be  constructed  from  a  minimum  of  wood  to  give  the 
greatest  cubical  content  ? 

His  dehberations  began  by  regarding  wine  as  the  precious 
content  enclosed  by  a  figure  in  space,  and  then  conceiving 
the  cask  as  representing  a  particular  class  of  "  bodies  of 
revolution,"  that  is,  of  figures  in  space  that  may  be  regarded 
as  produced  by  the  revolution  of  a  curved  Une  about  an  axis. 
At  this  point  he  at  first  endeavoured  to  gain  a  complete 
survey  of  the  question.  He  varied  the  boards  along  the 
sides,  the  staves,  and  formed  successively  ninety-two  such 
bodies  of  revolution,  some  of  which  he  named  after  the  fruits 


HIGHWAYS  AND  BY-WAYS  ITT 

which  they  resembled  in  shape,  as,  for  example,  apple-shaped, 
lemon-shaped,  olive-shaped  bodies.  He  started  out  by 
measuring  casks,  and  the  final  result  was  that  his  work, 
Doliometrie,  became  the  source  of  all  future  cubatures  or 
measurements  of  volume. 

Now  we  come  to  the  deciding  point.  What  conditions 
has  the  hmiting  surface  of  such  a  cask-Uke  body  of  revolution 
to  fulfil,  if  the  body  is  to  have  a  maximum  volmne  ?  An 
epochal  discovery  here  came  to  light.  The  practical  head  of 
the  house  soars  up  into  the  subhme  realms  of  the  theory  of 
magnitudes.  Kepler  discovered  the  conception  of  changes 
in  functions,  and  their  peculiarities  at  the  maximum  point. 
(He  did  not,  of  course,  use  these  modem  terms.)  By  this 
means,  long  before  Newton  and  Leibniz,  he  laid  the  founda- 
tions of  Infinitesimal  Calculus,  which  later  became  the  heart 
and  soul  of  mathematics,  of  astronomy,  of  theoretical  physics, 
and  of  technical  science,  in  so  far  as  it  is  foimded  in  mechanical 
relations. 

On  the  other  hand,  Einstein  who  now,  three  hundred  years 
later,  has  set  up  his  differential  equations,  and,  with  them,  a 
new  world-system,  stands  before  us  as  a  pure  discoverer, 
devoid  of  practical  aims.  But  in  these  equations  there  are 
elements  of  analysis  that  once  came  to  fight  in  a  happy  idyll. 
This  event  did  not  come  out  of  the  grey  obscurity  of  abstrac- 
tion, but  out  of  a  region  of  earthly  happiness,  when  a  ray  of 
light  found  its  way  into  Kepler's  gloomy  existence.  No  poet 
has  yet  expressed  this  curious  complex  of  events  in  a  ballad, 
teUing  how  Truth,  the  only  object  of  Science,  was  pressed  out 
of  the  grape,  and  how  Practice,  inspired  by  the  inquiry  of  a 
cooper,  found  its  way  to  a  Theory  that  stretches  to  the  confines 
of  the  Universe. 

II 

The  conversation  touched  on  famous  expressions,  words 
carved  in  stone,  in  particular  a  saying  of  Kant  which  seeks 
to  fix  the  foundation  and  the  limits  of  knowledge.  "  Every 
science  of  Nature,"  the  great  philosopher  of  Konigsberg 
had  said,  **  contains  just  as  much  Truth  as  it  contains  mathe- 
matics."   And  since,  ultimately.  Nature  includes  everything 

12 


178  EINSTEIN  THE  SEARCHER 

— for  a  demarcation  between  physical  and  mental  science  no 
longer  seems  possible — then,  if  we  follow  Kant,  we  should 
have  to  regard  mathematics  as  the  sole  measure  of  science. 

It  is  certainly  not  yet  possible  to  enter  into  a  discussion 
on  this  point  with  historians,  medical  or  legal  practitioners. 
They  would  be  justified  in  refusing  it,  since,  in  their  subjects, 
*'  truth  '*  is  not  the  sole  factor,  and  because  we  cannot  see  at 
present  how  the  conception  of  a  comprehensive  mathematical 
truth  is  to  find  a  place  in  them.  But  when  we  question  a 
physicist  on  this  point,  who  unceasingly  uses  mathematics 
as  his  chief  instrument,  we  should  surely  expect  him  to  answer 
with  an  unconditional  affirmative.  At  least,  I  should  not 
have  been  surprised  if  Einstein  had  answered  in  this  way, 
and  if  he  had  indeed  claimed  its  validity  for  every  branch  of 
science. 

But  Einstein  considered  this  quotation  to  be  true  only 
conditionally,  in  that  he  accepted  it  as  a  principle,  but  did  not 
regard  it  as  universal.  That  is,  he  does  not  recognize  mathe- 
matics as  the  only  test  of  truth. 

"  The  sovereignty  of  mathematics,'*  said  Einstein,  *'  is 
based  on  very  simple  assumptions ;  it  is  rooted  in  the  con- 
ception of  magnitude  itself.  Its  dominant  position  is  due  to 
the  fact  that  it  gives  us  much  more  delicate  means  of  dis- 
tingmshing  between  infinitely  varied  possibilities  than  any 
other  method  of  thought  that  expresses  itself  in  language 
and  is  restricted  to  the  use  of  words.  The  greater  the  field 
taken  into  consideration,  the  clearer  does  this  become  ;  but 
even  in  such  a  narrow  range  as  i  to  loo,  an  estimate  such 
as  27  is  incomparably  more  exact  than  can  be  expressed  in 
words  in  any  other  way.  If  we  think  of  a  series  of  sensations, 
ranging  from  pleasure  to  pain,  or  from  sweet  to  bitter,  we 
find  that  words  leave  us  in  an  uncertain,  confused  state, 
and  we  do  not  succeed  in  fixing  on  a  point  of  the  series  with 
the  same  precision  as  we  above  fixed  on  the  27  out  of  the  100. 
But  when  the  theory  of  magnitude  plays  a  part  in  the  question, 
as,  for  example,  in  a  series  of  tones,  whose  vibrations  exhibit  a 
mathematical  sequence,  we  immediately  attain  a  much  higher 
order  of  precision  by  using  numbers.  ..." 

That  is  why  there  is  a  sort  of  scientific  pleasure  in  the 
sequence  of  tones,  so  my  thoughts  ran  on.     Leibniz  remarks 


y 


HIGHWAYS  AND  BY-WAYS  179 

that  "  Music  is  the  pleasure  of  the  human  soul,  which  arises 
from  counting  without  knowing  that  it  is  counting."  Here 
Pythagoras'  *'  Number  is  the  essence  of  all  things  "  is  verified. 
As  soon  as  we  arrive  at  the  stage  at  which  we  feel  the  psycho- 
logical essence  of  number,  we  fall  into  a  sort  of  ecstasy, 
because,  in  our  subconscious  minds,  we  experience  not  only 
the  pleasure  of  sense  but  also  the  underiying  truth. 

Einstein  resumed :  "  Kant's  remark  is  correct  in  the 
sense  that  it  sets  up  two  things  in  clear  contradiction  to  one 
another.  On  the  one  hand,  he  has  in  view  the  fruits  of  know- 
ledge of  ordinary  life,  in  which  our  ordinary  perceptions  and 
experiences  are  intermingled  and  cannot  be  disentangled  by 
inductive  methods  and  deductive  considerations.  Opposed 
to  these,  and  to  be  regarded  of  higher  rank,  are  the  properly 
scientific  constructions — that  is,  such  in  which  we  find  a  neat 
differentiation  of  connected  thoughts  that  are  based  on  regular 
foundations  and  that  form  the  links  of  a  chain  of  deduction. 
Whenever  our  science  succeeds  in  detaching  this  logically 
ordered  knowledge  from  its  sense-sources,  it  has  a  mathe- 
matical character,  and  the  amount  of  truth  contained  in  it 
will  accordingly  be  determined  by  Kant's  criterion.  But  Kant 
demands  too  much  when  he  asks  us  to  apply  this  scale  to  all 
attainable  knowledge  of  science.  It  would  seem  advisable  to 
draw  Umitations  if  his  remark  is  to  serve  as  a  regulative 
measure.  A  great  part  of  biological  science  will  in  future 
still  be  obliged  to  make  its  way  independently  of  purely  mathe- 
matical considerations." 

"  Your  reflections.  Professor,  would  then  also  apply  to 
the  saying  of  Galilei :  The  book  of  Nature  lies  open  before 
us,  but  is  written  in  letters  other  than  those  of  our  alphabet ; 
its  characters  are  composed  of  triangles,  quadrilaterals,  circles, 
and  spheres." 

"  With  all  due  honour  to  the  beauty  of  this  observation,  I 
cannot  refrain  from  doubting  its  universal  validity.  If  we 
were  to  accept  it  unconditionally  we  should  have  to  regard 
the  paths  of  all  research  as  purely  mathematical,  and  this 
would  exclude  certain  very  important  possibihties,  above  all, 
certain  forms  of  intuition  that  have  shown  themselves  to  be 
extremely  fruitful.  Thus,  according  to  GaHlei's  interpreta- 
tion, the  book  of  Nature  would  have  been  illegible  for  Goethe, 


180  EINSTEIN  THE  SEARCHER 

for  his  spirit  was  entirely  non-mathematical,  indeed  anti- 
mathematical.  But  he  possessed  a  particular  form  of  intuition 
that  expressed  itself  as  a  feeling  which  put  him  into  direct 
contact  with  Nature,  with  the  result  that  he  obtained  a  clearer 
vision  than  many  an  exact  investigator." 

"  Do  you  then  consider  intuitive  gifts  to  be  separable  at 
all  in  form  and  in  kind  ?  " 

*'  It  would  be  pedantic  to  seek  to  establish  a  fundamental 
difference,  even  if  we  may  regard  the  non-mathematical 
intuition  of  Goethe  as  a  very  striking  case.  Moreover,  as  I 
have  often  emphasized,  all  great  achievements  of  science  start 
from  intuitive  knowledge,  namely,  in  axioms,  from  which 
deductions  are  then  made.  It  is  possible  to  arrive  at  such 
axioms  only  if  we  gain  a  true  survey  of  thought -complexes 
that  are  not  yet  logically  ordered  ;  so  that,  in  general,  intuition 
is  the  necessary  condition  for  the  discovery  of  such  axioms. 
And  it  cannot  be  denied  that,  in  the  great  majority  of  minds 
with  a  mathematical  tendency,  this  intuition  exhibits  itself  as 
a  characteristic  of  their  creative  power." 

"  From  these  remarks  it  would  appear  that  you  value 
deduction  considerably  higher  than  induction.  Perhaps  in 
using  these  catchwords  I  am  expressing  myself  a  Httle  vaguely  ; 
it  seems  to  me  that  great  things  have  been  achieved,  too,  by 
using  inductive  processes." 

"  Let  us  first  define  what  each  of  these  terms  means. 
Deduction  is  the  derivation  of  the  particular  from  the  general, 
whereas  induction  is  the  process  of  deriving  the  general  from 
the  particular  case.  Now,  quote  any  example  of  a  brilliant 
achievement,  which  you  feel  illustrates  the  power  of  the 
inductive  method.  Of  whatever  kind  your  example  may  be, 
you  will  soon  become  aware  of  the  difference  in  the  significance 
of  the  two  processes." 

"  For  me  the  most  perfect  example  of  induction  is  given  by 
certain  reasoning  of  Euchd.  The  question  was  whether  there 
is  a  finite  or  an  infinite  number  of  primes  (that  is,  numbers 
that  cannot  be  divided  without  leaving  a  remainder  except 
by  unity).  EucHd  found  an  elegant  proof  that  the  total 
number  is  infinite  by  the  following  strictly  inductive  reasoning. 
If  the  total  number  were  finite  there  would  have  to  be  a 
greatest  prime.     Let  us  call  it  n,  and  then  form  the  product 


HIGHWAYS  AND  BY-WAYS  181 

of  all  primes  up  to  n  and  including  it,  finally  adding  one, 
thus:  2x3x5x7x11x13  .  .  .  w,  plus  I.  This  new  number, 
say  Y,  is  certainly  greater  than  n,  and  now  there  are  two 
possibilities,  either  n  is  prime  or  it  is  not  prime. 

"  If  it  is  not  prime,  it  must  be  divisible  by  some  existing 
prime.  But  the  primes  up  to  and  including  n  cannot  divide 
exactly  into  Y,  as  there  is  always  a  remainder,  namely,  i. 
Hence  Y  must  be  divisible  by  an  existing  prime  X  greater 
than  n.  This  contradicts  the  assumption  that  n  is  the  greatest 
prime,  for^X^is  shown  to  be  greater  than  n. 

"  Secondly,  if  Y  is  a  prime,  it  immediately  follows  that  n 
cannot  be  the  greatest  prime,  for  Y  is  greater  than  n.  Hence, 
however  great  may  be  any  prime  that  we  may  assume,  there 
will  always  be  one  that  is  greater,  and  even  if  we  do  not 
succeed  in  expressing  it  in  figures,  we  see  that  it  must  certainly 
exist.  Thus  by  studying  carefuUy  a  particular  case — the 
prime  n,  which  was  assumed  to  be  the  greatest  possible  one — 
we  have  arrived  at  a  general  theorem  which  states  that  there 
is  no  Umit  to  the  number  of  primes.  Is  not  that,  too,  a  triumph 
of  intuition  ?  " 

**  Certainly,"  said  Einstein.     "  But  you  must  not  overlook 
the  fact  that  a  theorem  of  this  kind  cannot  be  ranked  with 
a  theorem  of  a  fimdamentally  axiomatic  character.     The  one 
you  havefdiscussed  has  been  derived  by  a  clever  process  of 
reasoning,    but  it  does  not   exhibit  the  characteristic  of  a 
momentous  discovery.     This  theorem  of  Euclid  can  be  im- 
agined absent  from  science  without  the  content  of  truth  in 
science  being  essentially  effected.     Compare  with  it  a  theorem 
of  axiomatic  significance,  such  as  Gahlei's  Law  of  Inertia,  or 
Newton's  Law  of  Gravitation.     Theorems  such  as  the  latter 
are  characterized  by  being  starting-points  of  knowledge  that 
are  inexhaustible  in  the  consequences  that  may  be  deduced 
from  them.     Your  question,  earher,  as  to  whether  I  consider 
the  deductive  method  superior  to  the  inductive,   was  not 
formulated  in  correct  terms.     To  this  I  answered  above  that 
the  inductive  method  as  a  means  of  discovering  general  truths 
usually   appears   over-estimated.     The   proper   form   of   the 
question  is  :   Which  truths  are  of  the  higher  order,  those  that 
are  found  inductively,  or  those  that  lead  to  further  deduction  ? 
There  can  scarcely  be  doubt  about  the  answer." 


182  EINSTEIN  THE  SEARCHER 

**  No,  that  is  certainly  true.  If  I  understand  your  meaning 
rightly,  the  answer  may  be  expressed  by  an  allegory.  In- 
tuition of  the  highest  order  creates  treasure-mines,  those  of 
lesser  degree  individual  articles  of  value  that  are  significant 
in  themselves,  although  they  cannot  be  compared  with  the 
inestimable  value  of  the  mines.  The  fact  that  the  highest 
intuition  is  found  in  minds  with  a  mathematical  trend  makes 
it  appear  possible  that  Kant's  remark  may  gain  more  and 
more  credence  in  the  future.  It  already  appHes  in  a  measure 
to  subjects  to  which  it  seemed  inappHcable  during  Kant's 
hfetime,  for  example,  in  Psychology,  in  which  the  relations 
between  stimulus  and  response  have  been  established  mathe- 
matically only  since  the  Weber-Fechner  Law  was  set  up  ; 
and  also,  since  the  time  of  Quetelet,  in  Moral  Science  and 
Sociology,  we  learn  from  mathematical  methods  of  statistics 
and  probability  that  even  Man  as  an  active  being  is  subjected 
to  mechanical  causaUty.  At  any  rate  it  seems  manifest  that 
Kant's  remark,  that  in  every  science  there  is  just  as  much 
truth  as  there  is  mathematics,  has  received  additional  support 
in  recent  times." 

'*  That  may  be  admitted,"  concluded  Einstein,  "  without 
recognizing  his  remark  as  an  axiom.  It  is  still  far  removed 
from  making  possible  unassailable  deductions,  and  will  never 
quite  succeed  in  doing  so  ;  yet  it  may  claim  equal  significance 
as  a  beautifully  expressed  idea  with  that  of  Pythagoras,  which 
asserts  number  to  be  the  nature  of  all  things." 


Ill 

"  The  lines  of  demarcation  between  '  conceptual  know- 
ledge '  (Erkennen)  and  *  perceptual  knowledge  '  (Kennen)  are 
being  drawn  more  and  more  closely  nowadays.  The  former 
is  regarded  as  being  the  exclusive  possession  of  the  highly 
developed  human  mind,  and  the  latter  as  being  characteristic 
of  the  lower  intelhgence  of  other  hving  creatures.  Is  this  not 
a  pronounced  case  of  anthropomorphism,  and  does  it  not 
mislead  us  to  form  opinions  that  we  should  at  once  disown 
if  we  succeed  in  stepping  out  of  our  human  frames  even^for 
a  moment  ?  " 


HIGHWAYS  AND  BY-WAYS  188 

"  We  have  to  rest  satisfied  with  anthropomorphism  once 
and  for  all,"  answered  Einstein,  **  and  there  is  no  sense  in 
wishing  to  escape  from  it,  for  the  arguments  about  anthropo- 
morphism are  necessarily  also  diffused  with  it,  itself.  We  are 
thus  moving  in  a  circle  if  we  imagine  we  can  deduce  something 
outside  of  human  knowledge.  As  soon  as  we  have  argued 
around  the  circle,  we  find  ourselves  again  at  the  starting- 
point,  and  so  we  are  compelled  to  mark  clear  Unes  of  division 
between  instinctive  knowledge,  derived  directly  by  perception, 
from  conceptual  knowledge,  derived  by  processes  of  abstraction 
and  reflection  ;  in  this  way  we  award  the  palm  of  supremacy 
to  the  human  mind." 

"  But  what  if  the  following  contradiction  were  to  assert 
itself  ?     Suppose  that  the  logical  '  circle  *  is  not  a  circle  at 
all,  but  a  spiral,  so  that  the  final  point  of  the  argument  hes 
just  a  trifle  above  the  initial  point.     I  feel  instinctively  that 
such  apparently  fruitless  circuitous  arguments  might  finally 
lead  to  a  definite  piece  of  knowledge.     For  example,  a  certain 
insect,  the  ichneumon-fly,  although  devoid  of  a  knowledge  of 
science  in  our  sense,  infaUibly  plants  its  sting  in  a  definite 
point  in  the  rings  of  a  caterpillar,  at  just  the  point  that  serves 
its  purpose  of  paralysing  the  caterpillar  without  killing  it. 
It  acts  instinctively,  and  it  is  open  to  me  to  interpret  this 
occurrence  in  other  words.     The  fly  discloses  that  it  *  knows  * 
the  anatomy  of  the  foreign  creature,  although  it  has  no  con- 
ceptual knowledge  of  it  in  our  sense.     But  it  immediately 
follows  from  this  analogy  that,  from  the  point  of  view  of  the 
fly,  its  perceptual  intelUgence  stands  higher  than  our  con- 
ceptual intelligence — that  is,  by  changing  the  perspective,  I 
am  led  to  declare  the  anatomical  knowledge  of  the  fly  to  be 
of  higher  rank  than  the  analogous  knowledge  of  the  most 
learned  anatomist.     In  the  same  way  I  might  persuade  myself 
that  the  mathematics  of  a  bird  of  passage  stands  above  the 
cartographic  knowledge  of  any  human  explorer.    The  migratory 
bird  that  flies  from  the  interior  of  Africa  in  a  straight  Hne  to 
its  nest  in  Mecklenburg  must  have  something  in  the  nature 
of  a  co-ordinate  system  in  its  organism.     The  real  reason  that 
we  assign  a  higher  position  to  our  conceptual  knowledge  is 
that  we  are  equally  proud  of  our  inteUigence  as  of  our  science  ; 
this  is  perhaps  a  deception  depending  on  some  compromise. 


184  EINSTEIN  THE  SEARCHER 

a  sort  of  illicit  deal  in  which  the  mind  draws  bills  of  exchange 
on  science,  and,  as  a  return,  science  meets  its  obligations  by 
paying  in  cheques  drawn  on  the  mind  !  " 

I  must  confess  that  these  hazardous  suggestions  received 
no  welcome  from  Einstein,  and  were  not  even  met  with  the 
friendly  smile  with  which  he  usually  accompanies  his  refuta- 
tions. Nor  do  I  disguise  from  myself  that  the  question  of 
conceptual  or  perceptual  knowledge  can  in  no  way  serve  as 
a  basis  of  proof  ;  we  may  at  most  base  certain  conjectures 
on  the  difference  of  these  types  of  knowledge,  conjectures 
that  suggest  in  words  what  eludes  our  clear  comprehension. 
Einstein's  refusal  to  allow  this  possibility  certainly  rests  on 
much  firmer  ground  than  the  somewhat  Bergsonian  views 
that  I  tried  to  present.  Perhaps  they  are  of  a  hair-spHtting 
nature,  and  deal  with  things  lying  on  different  planes  ;  and 
are  deduced  by  unjustifiably  altering  the  perspective  with  a 
sort  of  sophistic  somersault ;  perhaps  I  may  be  reproached 
with  seeking,  hke  Miinchhausen,  to  reach  a  higher  standpoint 
without  having  a  support  from  which  to  start.  Yet  how  is  it 
that  I  find  it  impossible  to  free  myself  from  this  chain  of 
thought  ?  No  reason  is  forthcoming,  for  it  is  a  purely  meta- 
physical question,  and  there  has  never  yet  been  a  clear  system 
of  metaphysics  free  from  ambiguities  and  sophism. 

Let  us  rather  confine  ourselves  to  the  conceptual  intelli- 
gence characteristic  of  human  beings,  with  which,  according 
to  Einstein,  so  many  pleasures  of  theory  are  available.  I 
asked  him  whether  he  would  recognize  differences  of  degree 
in  these  pleasures,  dependent  on  their  intensities.  Although 
I  rightly  felt  that  he  would  answer  in  the  affirmative,  his 
answer  took  a  totally  different  turn  from  what  I  had  expected. 
It  was,  indeed,  a  great  surprise,  for  in  the  matter  of  happiness 
of  spirit  he  expressed  a  view,  according  to  which  he — a  great 
discoverer  1 — does  not  regard  Science  as  the  deepest  source 
of  happiness  ! 

*'  Personally,"  said  Einstein,  "  I  experience  the  greatest 
degree  of  pleasure  in  getting  contact  with  works  of  Art.  They 
furnish  me  with  happy  feelings  of  an  intensity  such  as  I  cannot 
derive  from  other  realms." 

**  This  is  indeed  a  remarkable  revelation,  Professor!"  I 
exclaimed.    "  Not  that  I  have  ever  doubted  your  receptivity 


HIGHWAYS  AND  BY-WAYS  185 

for  products  of  art,  for  I  have  often  enough  observed  how  you 
are  affected  by  good  music,  and  with  what  interest  you  yourself 
practise  music.  But  even  at  such  moments  when  you  gave 
yourself  up  to  the  pleasures  of  the  Muses,  and  were  soaring  in 
regions  far  removed  from  the  earth,  I  used  to  say  to  myself : 
This  is  a  delightful  arabesque  in  Einstein's  existence ;  but  I 
should  never  have  surmised  that  you  regard  this  decorative 
side-issue  as  the  greatest  source  of  happiness.  But  your  con- 
fession seems  to  go  further,  perhaps  even  beyond  music  ?  " 

"  At  the  moment  I  was  thinking  particularly  of  hterature." 

**  Do  you  mean  literature  in  general  ?  Or  had  you  a 
definite  writer  in  mind,  when  you  were  speaking  of  the 
feUcitous  effect  of  works  of  art  ?  " 

"  I  meant  it  generally,  but  if  you  ask  in  whom  I  am  most 
interested  at  present,  I  must  answer  :  Dostojewski !  "  He 
repeated  the  name  several  times  with  increasing  emphasis. 
And,  as  if  to  deal  a  mortal  blow  at  every  conceivable  objection, 
he  added :  "  Dostojewski  gives  me  more  than  any  scientist, 
more  than  Gauss  !  " 

"  If,  Professor,"  said  I,  after  a  pause  that  may  easily  be 
accounted  for — "  if  you  mention  in  the  same  breath  the  names 
of  two  such  powerful  but  essentially  different  intellects,  you 
open  the  way  to  a  discussion  that  cannot  be  settled  by  a  mere 
positive  assertion.  It  is  possible  to  admire  intensely  Dosto- 
jewski as  one  who  moulds  personahties  and  who  analyses  the 
inner  struggles  of  the  soul,  and  yet  to  deny  him  perpetual 
fame.  This  depends  on  individual  judgment,  and,  as  for  my 
own,  I  believe  that  Dostojewski,  in  spite  of  his  direct  artistic 
appeal,  will  not  have  his  name  perpetuated  through  the 
centuries  Hke  that  of  many  another  member  of  Parnassus.  It 
seems  to  me  to  be  a  more  important  matter  whether  a  common 
measure  can  be  found  for  Art  and  Discovery  at  all.  Perhaps 
the  test  of  how  far  a  work  can  be  replaced  may  be  regarded 
as  vaUd  for  each.  When  you  say  that  Dostojewski  gives  you 
more  than  Gauss,  this  probably  corresponds  with  the  feeling 
that  without  Dostojewski  you  would  have  no  *  Karamasoffs  ' 
and  hence  would  lack  a  certain  life-value  that  cannot  be 
replaced.  But  if  Gauss  had  failed  to  produce  one  of  his  funda- 
mental theorems  of  Algebra,  probably  some  other  Gauss 
would  have  appeared,  who  would  have  achieved  this  result. 


186  EINSTEIN  THE  SEARCHER 

According  to  this,  then,  our  instinct  increases  the  value  of  a 
work  of  art,  as  we  feel  that  we  are  dependent  on  one  being 
alone  for  its  creation." 

**  But  this  is  only  to  be  admitted  conditionally,'*  said 
Einstein,  "  for  the  best  that  Gauss  has  given  us  was  likewise 
an  exclusive  production.  If  he  had  not  created  his  geometry 
of  surfaces,  which  served  Riemann  as  a  basis,  it  is  scarcely 
conceivable  that  anyone  else  would  have  discovered  it.  I 
do  not  hesitate  to  confess  that  to  a  certain  extent  a  similar 
pleasure  may  be  found  by  absorbing  ourselves  in  questions 
of  pinre  geometry." 

"  Perhaps  we  may  use  a  different  characteristic  as  a  means 
of  comparison,"  I  suggested,  "  namely,  the  permanency  of 
the  impression  produced  on  the  subject  receiving  it.  For 
example,  a  fine  piece  of  music  never  loses  its  influence.  We  can 
hsten  to  the  first  movement  of  Beethoven's  Ninth  Symphony 
a  hundred  times,  and,  although  we  know  at  every  beat  what 
will  follow,  the  state  of  pleasure  continues  unweakened ; 
indeed,  it  might  rather  be  said  that  the  expectation  of  pleasure 
increases  from  one  hearing  to  the  next." 

"  This  characteristic,  too,"  answered  Einstein,  "  cannot 
be  claimed  as  the  exclusive  property  of  works  of  art.  Its 
existence  cannot  be  doubted,  inasmuch  as  it  belongs  to  every 
eminent  example  of  art.  Yet  we  encounter  it  outside  the 
realm  of  art,  too,  in  great  advances  of  science,  with  which  we 
never  cease  occupying  ourselves,  and  yet  the  impression  con- 
tinues unweakened." 

"  Do  you  include  among  them  the  impressions  that  a 
discoverer  experiences  when  he  reviews  in  his  mind  the  progress 
due  to  his  own  efforts  ?  " 

"  Naturally,  and  these,  indeed,  quite  particularly  ;  and  if 
this  question  were  put  to  me  directly,  I  should  answer  un- 
hesitatingly that  I  find  pleasure  in  reflecting  on  my  own 
discoveries,  and  never  experience  feelings  of  weariness  in 
passing  over  them  again.  So  that,  to  return  to  our  original 
thesis,  we  must  adopt  a  new  basis  of  value  if  we  wish  to 
account  for  the  fact  that  the  greatest  degree  of  happiness  is 
to  be  expected  of  a  work  of  art.  It  is  the  moral  impression, 
the  feeling  of  elevation,  that  takes  hold  of  me  when  the  work 
of  art  is  presented.     And  I  was  thinking  of  these  ethical 


HIGHWAYS  AND  BY-WAYS  187 

factors  when  I  gave  preference  to  Dostojewski's  works.  There 
is  no  need  for  me  to  carry  out  a  literary  analysis,  nor  to  enter 
on  a  search  for  psychological  subtleties,  for  all  investigations 
of  this  kind  fail  to  penetrate  to  the  heart  of  a  work  such  as 
"  The  Karamasoffs."  This  can  be  grasped  only  by  means  of 
the  feeUngs,  that  find  satisfaction  in  passing  through  trying 
and  difficult  circumstances,  and  that  become  intensified  to  ex- 
ultation when  the  author  offers  the  reader  ethical  satisfaction. 
Yes,  that  is  the  right  expression,  '  ethical  satisfaction ' !  I 
can  find  no  other  words  for  it.'* 

His  whole  face  lit  up,  and  I  was  deeply  touched  by  his 
expression.  At  that  moment  it  seemed  to  me  that  he  had 
drawn  the  last  veil  from  his  soul  to  allow  me  to  share  in  his 
ecstasy.  Was  that  the  same  physicist  who  interprets  the 
events  of  the  world  in  terms  of  mathematics,  and  whose 
equations  encompass  phenomena  from  electrons  to  universes  ? 
If  so,  it  was  a  different  soul ;  one  which  gave  utterance,  like 
that  of  Faust,  to  the  words  : 

"  And  when  in  the  feeling  wholly  blest  thou  art. 
Call  it  then  what  thou  wilt. 
Call  it  Bhss  !     Heart  !     Love  I     God  I 
I  have  no  name  for  it  I 
FeeUng  is  aU  in  all ! 
Name  is  but  sound  and  reek, 
A  mist  round  the  glow  of  heaven  I  " 

And,  certainly,  the  book  need  not  have  been  one  of 
Dostojewski's  to  excite  this  feehng  in  him.  He  chose  the 
latter  to  give  expression  to  a  mood  that  may  change  according 
to  what  he  reads,  but  undergoes  no  fluctuations  in  its  ethical 
foundation.  From  other  occasions  we  know  how  little  ethics, 
that  is  conducted  along  systematic  fines,  signifies  to  him,  and 
that  he  does  not  even  include  it  in  the  sciences.  But  at  the 
same  time  we  see  now  that  his  inner  fife  is  dominated  entirely  by 
the  ethical  principle.  His  deep  love  of  Art  is  characterized  by 
it,  and  receives  full  satisfaction  from  the  source  of  ethical  joy  of 
which  Art  is  the  centre. 

IV 

During  the  autumn  of  1918  Einstein  was  feehng  indisposed, 
and,  on  the  advice  of  his  doctor,  did  not  leave  his  bed.     When 


188  EINSTEIN  THE  SEARCHER 

I  entered  his  room,  I  saw  at  once  that  there  was  no  reason 
for  alarm,  for  pieces  of  paper  covered  with  mysterious  symbols 
were  l5Hing  about,  and  he  was  absorbed  in  making  additions 
to  some  of  them.  Nevertheless,  I  considered  it  my  duty  to 
treat  him  as  a  patient  under  medical  care,  and  did  not  conceal 
my  intention  of  leaving  him  after  having  inquired  about  his 
condition.  But  he  would  not  accept  my  visit  as  a  mere  call 
to  ascertain  his  progress  towards  recovery,  and  insisted  that 
I  should  remain  with  him  a  while,  to  converse  about  amusing 
little  problems  as  usual.  y 

I  pointed  out  to  him  that  there  were  two  objections  to 
this,  the  first  being  that  he  was  unwell,  and  the  second  that  I 
was  intruding  on  his  work. 

"  How  illogical !  "  he  answered.  "  If  I  interrupt  my  work 
to  chat  with  you,  I  am  putting  aside  exactly  what  the  doctor 
would  deny  me  if  I  were  to  allow  him.  So,  let  us  make  a 
start.  You  have  probably  some  conundrum  weighing  on  your 
mind." 

"  That  may  not  be  far  wrong.  I  have  been  troubled  by 
something  in  connexion  with  Kepler's  second  law.  It  almost 
robbed  me  of  my  night's  sleep.  My  thoughts  kept  returning 
to  a  certain  question,  and  I  should  like  to  know  whether  there 
is  any  sense  in  the  question  itself  at  all." 

"  Let  us  hear  it  !  " 

"  The  law  in  question  states  that  every  planet  in  describing 
its  elliptic  path,  sweeps  out  with  its  radius  vector  equal 
sectorial  areas  in  equal  intervals  of  time.  But  this  seems 
only  half  a  law,  for  the  radius  vectors  are  only  considered 
drawn  from  the  one  focus  of  the  ellipse,  namely,  the  gravita- 
tional centre.  Now,  another  focus  exists,  that  may  be  situated 
in  space  somewhere,  perhaps  far  away  in  totally  empty  regions, 
if  we  assume  the  orbit  to  be  very  eccentric.  My  question  is  : 
What  form  does  this  law  take  if  the  radius  vectors  are  drawn 
from  this  second  focus  and  if  the  corresponding  sectorial  areas 
are  considered,  instead  of  these  quantities  being  referred  to 
the  first  focus  exclusively  ?  " 

'*  This  question  is  not  devoid  of  sense,  but  it  serves  no 
useful  purpose.  It  may  be  solved  analytically,  but  would 
probably  lead  to  very  complicated  expressions,  that  would 
be  of  no  interest  for  celestial  mechanics.     For  the  second 


HIGHWAYS  AND  BY-WAYS  189 

focus  is  only  a  constructive  addition,  that  has  nothing 
real  in  space  corresponding  to  it.  What  else  is  troubUng 
you  ?  " 

**  My  next  difficulty  is  a  Uttle  problem  that  sounds  quite 
simple  and  yet  is  sufficiently  awkward  to  make  one  rack  one's 
brains.  It  was  suggested  to  me  by  an  engineer  who  certainly 
has  a  keen  mind  for  such  things,  and  yet,  as  far  as  I  could 
judge,  he  did  not  get  a  solution  for  it.  It  concerns  the  position 
of  the  hands  of  a  clock." 

*'  You  surely  are  not  referring  to  the  children's  puzzle 
of  how  often  and  when  both  hands  coincide  in  position  ?  " 

"  By  no  means.  As  I  said  just  now,  it  is  really  quite  per- 
plexing. Let  us  assume  the  position  of  the  hands  at  twelve 
o'clock,  when  both  hands  coincide.  If  they  are  now  inter- 
changed, we  still  have  a  possible  position  of  the  hands,  giving 
an  actual  time.  But,  in  another  case,  say,  exactly  six  o'clock, 
we  get  a  false  position  of  the  hands,  if  we  interchange  them, 
for  on  a  normal  clock  it  is  impossible  for  the  large  hand  to 
be  on  the  six  whilst  the  small  hand  is  on  the  twelve.  The 
question  is  now :  When  and  how  often  are  the  two  hands 
situated  so  that  when  they  are  interchanged,  the  new  position 
gives  a  possible  time  on  the  clock  ?  " 

"  There,  you  see,"  said  Einstein,  **  that  is  just  the  right 
kind  of  distraction  for  an  invalid.  It  is  quite  interesting,  and 
not  too  easy.  But  I  am  afraid  the  pleasure  will  not  be  of 
great  duration,  for  I  already  see  a  way  to  solve  it." 

Supporting  himself  on  his  elbow,  he  sketched  a  diagram 
on  a  sheet  of  paper  that  gave  a  clear  picture  of  the  conditions 
of  the  problem.  I  can  no  longer  recollect  how  he  arrived  at 
the  terms  of  his  equation.  At  any  rate,  the  result  soon  came 
to  hand  in  a  time  not  much  longer  than  I  had  taken  to  enunciate 
the  problem  to  him.  It  was  a  so-called  indeterminate  (Dio- 
phantic)  equation  between  two  unknowns,  that  was  to  be 
satisfied  by  simple  integers  only.  He  showed  that  the  desired 
position  of  the  hands  was  possible  143  times  in  12  hours, 
an  equal  interval  separating  each  successive  position ;  that 
is,  starting  from  twelve  o'clock,  the  two  hands  may  be  inter- 
changed every  5  minutes  ttu  seconds,  and  yet  give  a  possible 
time. 


190  EINSTEIN  THE  SEARCHER 

I  mention  this  little  episode,  which  is  insignificant  in  itself, 
merely  to  give  an  example  of  how  a  great  discoverer,  too, 
finds  amusement  in  such  distractions.  In  Einstein's  case  this 
tendency  to  practise  his  ingenuity  on  unimportant  trifles  is 
so  much  the  more  pronounced  from  the  fact  that  he  requires 
an  outlet  for  his  virtuosity  in  calculation,  and  gratefully 
welcomes  every  suggestion  that  helps  him  to  relieve  his  mental 
tension.  Similar  characteristics  are  reported  of  the  great 
Euler,  as  well  as  of  Fermat,  whereas  many  another  eminent 
mathematician  feels  decidedly  unhappy  if  he  drifts  within 
reach  of  the  realm  of  actual  numerical  calculation.  In  my 
mind's  eye  I  still  see  Ernst  Kummer,  the  splendid  savant 
(who,  in  his  time,  conferred  distinction  on  Berlin  University 
by  his  very  presence),  suffering  agonies  whenever  ordinary 
arithmetical  tables  threatened  to  appear  in  the  working-out  of 
his  formulae.  As  a  matter  of  fact,  these  two  things,  a  mastery 
over  mathematics  and  a  talent  for  ingenious  calculation,  are 
to  be  considered  as  quite  independent,  even  if  we  now  and 
then  find  them  present  in  the  same  person. 

In  the  case  of  Einstein  this  tendency  is  a  symptom  of  an 
incredible  universality  of  spirit.  It  moreover  presents  itself 
in  the  pleasant  est  forms,  and  a  character-sketch  of  Einstein 
would  be  incomplete  if  this  trait  were  not  mentioned.  Every 
problem  which  is  in  any  way  amusing  excites  in  him  a  willing 
interest  and  enthusiasm.  I  once  directed  our  conversation 
to  the  so-called  Scherenschnitte.  These  are  made  from 
long  strips  of  paper  or  canvas,  the  ends  of  which  are  caused 
to  overlap  a  Httle  and  then  pasted  together,  but  instead  of 
being  fixed  so  that  a  flat  wheel  results,  which  rolls  on  one  side 
of  the  strip,  the  strip  is  twisted  one  or  more  times  before  the 
ends  are  fastened  together.  If  now  the  strip  is  cut  lengthwise 
right  along  its  centre,  various  unexpected  results  occur,  depend- 
ing on  the  number  of  twists  that  have  been  made  before  pasting. 

Some  very  complex  geometrical  difliculties  are  involved  in 
these  problems.  This  is  shown  by  the  fact  that  learned 
mathematicians  have  written  extensive  disquisitions  on  these 
curious  constructions  (for  example.  Dr.  Dingeldey's  book, 
published  by  Teubner,  Leipzig).  Einstein  had  never  taken 
notice  of  these  wonders  of  the  scissors,  but  when  I  began  to 
form  these  strips,  to  paste  them,  and  to  cut  them,  he  immedi- 


HIGHWAYS  AND  BY-WAYS  191 

ately  became  interested  in  the  underlying  problem,  and  pre- 
dicted in  a  flash  what  puzzUng  chain  constructions  would 
result  in  each  case,  with  a  certainty  that  would  lead  one  to 
imagine  that  he  had  spent  days  at  it.  On  another  occasion 
a  space-problem  dealing  with  dress  came  up  for  discussion  : 
Can  a  properly  dressed  man  divest  himself  of  his  waistcoat 
without  first  taking  off  his  coat  ?  One  would  not  have  dared 
to  confront  Copernicus  or  Laplace  with  such  a  problem. 
Einstein  at  once  attacked  it  with  enthusiasm,  as  if  it  were  an 
exercise  in  mechanics,  the  body  being  the  object  ;  he  solved  it 
in  a  trice,  practically,  with  a  little  energetic  manipulation, 
much  to  the  amazement  and  joy  of  the  beholder,  who  asked 
himself :  Is  this  the  same  Einstein  who  developed  the  work 
of  Copernicus  and  Newton  ?  A  little  later,  perhaps,  the  con- 
versation centres  around  some  serious  point  drawn  from 
poUtics,  political  economy,  sociology,  or  jurisprudence.  What- 
ever it  may  be,  he  knows  how  to  spin  out  the  suggested  thread, 
to  establish  contact  with  his  partner  in  conversation,  to  open 
up  his  own  perspectives  without  ever  insisting  on  his  point 
of  view,  always  stimulating  and  showing  a  ready  S5mipathy 
for  the  subject  of  discussion  and  for  all  the  ideas  which  it 
crystaUizes,  the  prototype  of  the  scientist,  in  the  mouth  of 
whom  Terence  put  the  words  :  "  I  am  a  human  being  ;  nothing 
that  is  human  is  alien  to  me  !  " 


CHAPTER  IX 
AN  EXPERIMENTAL  ANALOGY 

Forms  of  Physical  Laws. — Aids  to  Understanding. — Popular  Descriptions. 
— Optical  Signals. — Simultaneity. — Experiments  in  Similes. 

I  WISH  to  ask  you,  Professor,  to  help  me  over  a  difficulty 
and  to  treat  me  as  the  spokesman  of  a  great  number 
who  are  similarly  troubled.  In  most  accounts  of  your 
theory  of  relativity,  there  is  a  dearth  of  definite,  concrete, 
illustrative  examples  on  which  we  can  fix  our  minds  whenever 
the  theorem  is  to  be  applied  generally  without  limitation. 
Let  me  express  this  more  precisely  :  Your  simplified  picture 
of  the  structure  of  the  universe  is  achieved  in  the  theory  of 
relativity  by  emancipating  all  observations  from  fixed  co- 
ordinate systems,  and  by  proclaiming  the  equivalence  of  all 
systems  of  reference.  One  of  your  earliest  theorems  states 
that  physical  laws  describing  how  the  states  of  physical 
systems  alter,  remain  the  same,  no  matter  to  which  of  two 
co-ordinate  systems  these  states  are  referred,  provided  that 
the  co-ordinate  systems  are  moving  rectilinearly  and  uniformly 
relatively  to  one  another.  This  theorem  entails  the  following 
statement .  If  we — erroneously — adopt  a  non-relativistic  view, 
we  shaU  come  to  the  conclusion  that  physical  laws  depend  on 
the  particular  system  of  reference  chosen,  and  will  thus  assume 
a  different  form  for  each  different  system.  At  this  point  we 
experience  a  desire  to  hear  definite  examples.  What  varying 
forms  may  a  certain  given  physical  law,  known  under  a  definite 
form,  assume,  and  how  can  we  use  this  law  to  show  that  it 
must  adapt  itself  to  the  postulate  of  relativity  ?  " 

Einstein  explained  that  such  examples  cannot  be  given 
in  special  cases,  but  only  in  very  general  terms.  If  we  were 
to  suggest  the  elliptic  orbits  of  the  planets  (at  which  I  had 

192 


AN  EXPERIMENTAL  ANALOGY  198 

hinted  in  my  remarks),  we  should  fall  into  error,  for  the  law 
of  elliptic  orbits  is  no  such  law.  For,  from  another  point  of 
view,  the  elUptic  paths  of  the  planets  might  be  drawn  out  into 
wavy  lines,  or  into  spirals,  and  they  would  remain  ellipses 
only  as  long  as  the  lines  of  motion  are  referred  to  the  central 
attracting  body.  But  the  constancy  of  the  velocity  of  Ught 
is  such  a  law,  as  also  is  the  law  of  inertia,  according  to  which 
a  body  that  is  left  to  itself  moves  uniformly  in  a  straight  line. 
I  confessed  to  him  that  this  limitation  to  a  few  very  general 
laws  would  be  a  painful  matter  for  many  an  enthusiast  of 
average  attainments,  who  has  great  difficulty  in  distinguishing 
the  laws  that  are  generally  valid  from  those  that  hold  only 
within  circumscribed  limits.  But  if  this  were  not  so,  we  should 
have  to  alter  our  conception  of  what  is  conveyed  by  a  popular 
exposition.  For  it  is  called  popular,  not  because  it  now  and 
then  uses  the  patronizing  words  "  dear  reader,"  but  because 
it  anticipates  the  questions  and  doubts  of  the  man  of  average 
sense,  and  examines  them,  proving  some  to  be  unjustified 
and  others  to  be  reasonable  or  unreasonable,  as  the  case  may 
be.  "  Then  there  is  a  further  matter  that  troubles  me,"  I 
continued.  "  Let  us  suppose  an  ordinary  reader  of  such  a 
popular  account  to  get  a  first  insight  into  the  new  conception 
of  Time.  He  is  glad  to  feel  the  ideas  dawning  in  him,  and,  to 
get  a  more  lasting  view  of  the  idea,  he  repeats  the  arguments 
through  which  he  has  just  threaded  his  way,  and,  in  doing  so, 
again  encounters  the  phrase  '  uniform  motion.'  At  the  first 
reading  he  imagined  that  he  understood  the  expression  quite 
well,  but  the  second  time  he  pauses  and  considers.  For  now 
that  he  knows  how  much  depends  on  it,  he  is  anxious  to  find 
out  the  exact  meaning  of  a  '  uniform  motion.'  He  looks  for  a 
definition,  and  if  he  cannot  find  one  in  the  book  he  is  perusing, 
he  endeavours  to  reason  it  out  for  himself.  With  good  luck 
he  arrives  at  the  usual  statement  :  a  body  moves  with  *  uni- 
form motion  '  if  it  traverses  equal  distances  in  equal  intervals 
of  time.  But  equal  intervals  of  time  are  clearly  those  during 
which  a  body  in  uniform  motion  traverses  equal  distances. 
In  other  words,  he  explains  A  by  means  of  B,  and  B  by  means 
of  A,  so  that  he  has  involved  himself  in  a  vicious  circle  from 
which  he  cannot  escape.  This  is  his  hour  of  need,  due  to  the 
difficulty  of  '  time.' 
13 


194  EINSTEIN  THE  SEARCHER 

'*  He  hopes  that  further  study  will  remove  this  obstacle. 
He  meets  with  the  conception  of  '  simultaneity/  which  is 
defined  for  him  anew,  and  is  disclosed  as  being  *  relative.' 
He  manoeuvres  further  towards  the  fundamental  theorem  that 
every  body  of  reference  has  its  own  particular  time. 

**  His  popular  booklet  makes  this  clear  to  him  by  quoting 
the  example  of  a  flying-machine,  or,  better  still,  a  railway  train 
that  is  rushing  along  an  embankment  at  a  very  great  speed, 
and  that  carries  a  passenger.  Two  strokes  of  lightning  I  and  II 
are  to  take  place  at  two  widely  distant  points  on  the  embank- 
ment. The  question  is  then  :  When  are  these  two  flashes 
of  lightning  to  be  considered  '  simultaneous  '  ?  What 
conditions  must  be  fulfilled  to  ensure  this  ?  It  is  found — 
incontrovertibly — ^that  the  light -rays  starting  out  from  the 
two  strokes  of  lightning  must  meet  at  the  mid-point  of  the 
embankment. 

"  It  now  follows  from  a  short  chain  of  argument  that  the 
observer  in  the  train  will  see  flash  II  earlier  than  flash  I, 
if  they  reach  the  observer,  who  is  at  rest,  at  the  same  moment. 
That  is,  two  events  that  are  simultaneous  with  respect  to  the 
embankment  are  not  simultaneous  for  a  moving  system  (such 
as  a  train  or  a  flying-machine)  ;  the  converse  is,  of  course, 
also  true. 

"  Here,  again,  the  eager  layman  encounters  difficulty,  for 
he  asks  himself  :  Why  should  the  two  events  be  characterized 
or  defined  by  lightning-flashes  in  particular  ?  If  acoustic 
signals  were  used  instead,  nothing  would  be  altered  in  the 
fundamental  determination,  for  the  sound  rays  (sound-waves) 
would  likewise  meet  at  the  mid-point  of  the  line  joining  the 
sources  of  disturbance.  What  is  the  reason  that  the  relativity 
of  time  arises  only  when  phenomena  are  regarded  optically, 
and  that  rays  of  light  play  the  deciding  part  in  all  later  develop- 
ments ? 

*'  And  this  particular  query  is  followed  by  one  which  is  more 
general :  Why  does  the  popular  pamphlet  not  read  this  question 
in  my  mind  ?  I  know  that  the  author  of  it  is  more  skilled  in 
these  matters  than  I,  but  just  this  superiority  should  help  him 
to  divine  what  is  passing  in  my  mind  when  I  make  efforts  to 
follow  his  reasoning." 

Einstein  had  listened  to  me  patiently,  and  then  he  explained 


AN  EXPERIMENTAL  ANALOGY  195 

to  me  at  considerable  length  why  in  this  case  optical  signals 
cannot  be  replaced  by  sound  signals  :  hght  is  the  only  mode  of 
motion  that  shows  itself  to  be  entirely  independent  of  the 
carrier  of  the  motion,  of  the  transmitting  medium.  Thus  the 
constancy  of  velocity  is  assumed  in  the  above  argument,  and 
as  this  constancy  is  an  exclusive  property  of  light,  every  other 
method  must  be  discarded  as  unallowable  for  investigating 
the  conception  "  simultaneity."  Furthermore,  he  showed  me 
how,  on  the  basis  of  relativity,  starting  from  the  embankment - 
experiment,  we  may  arrive  at  a  perfectly  consistent  representa- 
tion of  the  conception  of  Time.  He  certainly  did  this  by 
applying  subtle  physical  arguments  that  exceed  the  scope  of 
the  present  book.*  He  added,  in  substance,  that  it  was 
futile  and  impossible  to  discuss  in  detail  all  the  conceivable 
objections  that  might  arise  in  the  mind  of  one  reading  a  popular 
work  of  this  kind  :  it  was  a  futile  undertaking,  because  the 
true  purpose  was  defeated,  inasmuch  as  a  clear  development 
of  the  fundamental  thought  would  be  almost  impossible  under 
the  cross-fire  of  so  many  random  questions. 

Thus,  in  this  matter,  Einstein  takes  the  same  stand  as 
Schopenhauer  in  the  preface  of  his  chief  work,  in  which  he 
says  :  "  To  understand  this  work  no  better  way  can  be  advised 
than  to  read  it  twice  (at  least),  inasmuch  as  the  beginning 
assumes  the  end,  almost  as  much  as  the  end  assumes  the 
beginning ;  the  smallest  part  cannot  be  understood  if  the 
whole  has  not  already  been  understood."  Whoever  accepts 
and  follows  this  advice  will  find  that  the  intermediate  objec- 
tions will  gradually  balance  and  cancel  one  another,  and  that 
it  is  not  necessary  that  they  should  interrupt  the  steady  and 
consistent  line  of  development. 

The  position  would  be  different  if  a  disciple  of  the  new 
theory  should  resolve  to  dispense  with  strictly  scientific  reason- 
ing altogether,  and  should  wish  to  meet  the  wishes  of  his 
readers  or  hearers  by  discarding  accuracy  entirely.  Such  a 
programme  seems  quite  feasible. 

*  In  these  arguments,  arrangements  of  synchronous  clocks  occur,  which 
are  fixed  into  the  co-ordinate  systems,  the  positions  of  their  hands  being 
compared  with  one  another.  The  "  time  "  of  an  event  is  then  defined  as 
the  position  of  the  hands  of  a  clock  immediately  adjacent  to  the  scene  of  the 
event. 


196  EINSTEIN  THE  SEARCHER 

"  This  would  be  merely  following  the  sketchy  method  of  a 
magazine,"  Einstein  remarked,  "  but  you  do  not  seriously 
think  that  it  would  lead  to  anything  ?  " 

"  It  would  not  be  a  true  explanation,  which  is  reserved  for 
technical  productions.  But  I  can  imagine  that  it  would  not 
be  unprofitable  to  help  one  who  is  entirely  ignorant  on  these 
questions  by  using  makeshifts,  in  the  form  of  allegories  or 
analogies,  which  will  serve  as  supports  if  he  should  take  fright 
during  the  course  of  his  earlier  studies.  These  shocks  are 
bound  to  occur,  as,  for  instance,  when  he  learns  that  a  moving 
rigid  rod  undergoes  contraction  in  the  direction  of  motion." 

"  But  this  is  proved  to  him  !  " 

"  Nevertheless,  he  does  not  easily  accept  it.  For  the 
general  reader  will  say  to  himself  :  *  A  superhuman  effort  is 
imposed  on  my  mind.  A  rigid  rod  is  the  most  constant  of  all 
things,  and  never  before  has  one  been  compelled  to  regard 
something  that  is  constant  as  variable.'  " 

"  If  he  does  not  grasp  it,  no  analogy  will  teach  him." 

"  But  perhaps  it  is  possible.  The  analogy  is  to  show  him 
that  the  effort  is  not  superhuman,  and  that  thinking  Man  has 
already  had  occasion  to  become  familiar  with  such  trans- 
formations from  constant  to  variable  factors." 

"  I  am  afraid  your  analogy  will  prove  a  failure." 

"  From  the  scientific  point  of  view  this  is  probably  true, 
inasmuch  as  all  comparisons  are  imperfect,  but  the  analogy 
may  yet  be  of  service  as  a  last  resort.  For  example,  I  should 
say  to  my  general  reader  :  '  Picture  to  yourself  a  savant  of  the 
Middle  Ages  who  reflects  on  the  constitution  of  animals  and 
plants.  One  fact  seems  to  him  to  be  irrevocably  true,  namely, 
that  the  species  are  unchangeable  !  A  palm  tree  is  a  palm 
tree,  a  horse  is  a  horse,  a  worm  a  worm,  and  what  is  once  a 
reptile  remains  a  reptile.  A  species  in  itself  denotes  something 
absolutely  invariant." 

**  The  expression  is  wrong  when  taken  in  this  connexion  ; 
you  mean  invariable.'* 

"  A  Httle  inaccuracy  more  or  less  does  not  affect  the 
analogy.  For  the  sake  of  my  picture  I  should  like  to  retain 
the  conception-couple,  variable  and  invariant.  Well,  then, 
the  species  give  our  savant  the  impression  of  invariance,  as 
in  the  view  that  was  held  by  Linn6  and  Cuvier.    This  view 


AN  EXPERIMENTAL  ANALOGY  197 

necessarily  has  its  counterpart  in  his  thought.  He  argues 
that  every  species  has  its  own  original  root,  and  that,  in  this 
sense,  there  is  very  extensive  variation.  The  fundamental 
roots  are  extremely  manifold ;  Nature  has  produced  in- 
numerable variations  in  her  individual  acts  of  creation.  But 
now  the  Theory  of  Descent  of  Lamarck,  Goethe,  Oken,  Geoff roy 
St.  Hilaire,  enters  the  field  and  produces  a  complete  inversion 
of  these  two  elements  ;  the  two  parts  of  the  earlier  point  of 
view  change  places.  Our  savant  has  to  revise  his  whole  world 
of  thought.  Now  all  organisms  are  to  be  traced  back  to  a 
single  original  root  :  the  latter,  which  was  variable  before, 
becomes  an  invariable  unicellular  primitive  organism,  but  the 
apparently  unchangeable  species  now  becomes  variable,  in  the 
widest  possible  sense.  And  even  if  this  savant  should  ex- 
claim :  *  How  am  I  to  reconcile  myself  to  this  view  ?  *  his 
descendants  later  find  no  difficulty  in  accepting  the  idea  that 
the  organic  roots  are  uniform,  and  that  it  is  the  species  that 
are  subject  to  all  manner  of  variation  as  a  compensating 
feature." 

Einstein  expressed  himself  very  little  pleased  with  this 
attempt  at  an  analogy,  and  found  that  it  was  so  far  fetched 
that  it  could  not  be  considered  admissible. 

"  Then  I  must  ask  your  permission  to  continue  my  at- 
tempt ;  perhaps  something  useful  may  yet  result  from  it. 
I  now  picture  to  myself  a  human  being  who  lived  in  classical 
times  and  who,  following  Ovid  and  the  great  majority  of  his 
contemporaries,  regards  the  earth  as  a  disc.  On  this  disc, 
each  inhabitant  of  the  earth  has  his  own  particular  position, 
for  the  disc  has  a  centre  with  reference  to  which  the  position 
of  a  person  can  be  specified  if  his  distance  and  his  angular 
displacement  from  a  given  initial  radius  is  specified.  Thus, 
there  is  a  variation  of  position  if  various  persons  are  considered. 
On  the  other  hand,  the  Above  and  the  Below  is  absolutely 
invariable  for  all  persons,  for  the  Hues  running  between  Above 
and  Below  are  all  parallel  for  them,  since  they  all  have  uni- 
formly the  same  disc  under  their  feet  and  the  same  heaven 
above  their  heads.  Ovid  would  therefore  have  refused  to 
entertain  for  a  moment  the  suggestion  that  Above-Below  is  a 
variable.  But  his  distant  descendants  accepted  the  view  that 
the  earth  is  spherical  and  that  there  are  antipodes  as  self- 


198  EINSTEIN  THE  SEARCHER 

evident,  and  they  found  not  the  slightest  difficulty  in 
considering  the  line  Above-Below  to  vary  with  their  own 
position,  making  all  possible  angles  with  an  initial  line  extend- 
ing to  direct  oppositeness.  Referred  to  the  centre  of  the  sphere, 
all  people  have  now  an  *  invariant  '  position,  whereas,  in 
compensation,  the  Above-Below  is  subject  to  every  conceivable 
variation.  And  now  I  again  address  myself  to  the  average 
reader,  and  say  that  the  meaning  of  these  analogies  is  that 
every  doctrine  that  leads  to  a  great  uniformity  converts  what 
was  formerly  invariant  into  a  variable  quantity,  and  vice 
versa.  The  theory  of  relativity  makes  all  considerations  about 
the  physical  world  independent  of  all  co-ordinate  systems ; 
it  establishes  completely  invariable  uniformity,  removed  from 
all  changes  due  to  varying  points  of  view.  Hence  what  was 
previously  invariable — such  as  a  rigid  measuring-rod — will 
now  become  variable.  It  is  not  surprising  that  this  requires 
a  new  method  of  thought,  a  revision  of  our  mode  of  reasoning, 
for  the  above  analogies  show  that  these  radical  adjustments 
are  characteristically  necessary  in  the  case  of  comprehensive 
theories,  and  that  such  theories  are  able  to  overcome  appar- 
ently firmly  established  ideas.  The  parallels  that  I  drew 
above  will  at  least  inspire  the  average  reader  with  a  certain 
confidence,  for  they  show  him  how  results  of  reasoning  that 
were  once  considered  incredible  were  regarded  as  self-evident 
by  later  generations." 

I  have  already  emphasized  sufficiently  that  Einstein 
regards  as  inadequate  these  auxiliary  pictures  that  have 
presented  themselves  to  me.  Yet  in  the  course  of  the  conversa- 
tion I  gained  the  impression  that  his  judgment  grew  somewhat 
milder,  and  that,  with  certain  reservations,  he  was  disposed 
to  let  them  pass  as  tolerably  useful  helps — and  they  are  not 
intended  to  be  more  than  this.  I  think,  therefore,  that  I 
am  not  acting  counter  to  his  wishes  in  citing  these  allegorical 
examples  here,  particularly  as  they  arose  in  the  course  of  our 
talks. 

Since  then,  I  have  had  many  opportunities  of  testing  these 
examples  on  certain  persons,  and  may  mention  that  they 
proved  quite  useful.  Analogies  of  this  kind  may  offer  a 
friendly  help  in  moments  when  the  uninitiated  feel  themselves 
in  peril,  and  encounter  a  difficulty  which  they  imagine  to  be 


AN  EXPERIMENTAL  ANALOGY  199 

insurmountable.  They  do  not  remove  the  difficulty,  but  they 
impart  a  certain  power  of  expansion  to  the  intellect  and 
encourage  a  continuation  of  effort,  which  would  probably 
otherwise  be  relaxed  at  the  first  sign  of  something  which  is 
imagined  to  be  inconceivable.  There  is  thus  no  room  in 
textbooks  for  such  helps,  but  they  may  justifiably  find  a 
place  in  a  book  that  departs  from  the  methodical  route,  and 
hopes  to  discover  in  by-wa}^  things  that  are  suggestive  and 
instructive. 


CHAPTER   X 
DISCONNECTED  SUGGESTIONS 

Conditionality  and  Unconditionality  of  Physical  Laws. — Conception  of 
Temperature. — Grain  of  Sand  and  Universe. — Are  Laws  unalterable  ? — 
Paradoxes  of  Science. — Rejuvenation  by  Motion. — Gain  of  a  Second. — 
Deformed  Worlds. — Atomic  Model, — Researches  of  Rutherford  and  Niels 
Bohr. — Microcosmos  and  Macrocosmos. — Brief  Statement  of  the  Principle 
of  Relativity. — Science  with  reduced  Sense-Organs. — Eternal  Repetition. — 
Higher  Types  of  Culture. 

IN  all  branches  of  reasoning,  no  word  and  no  conception 
has  played  a  more  important  part  than  that  of  law. 
Phj^ical  laws  denote  the  barrier  that  separates  strictly 
chance  and  arbitrariness  from  necessity,  and  it  seems  to  us 
that  the  region  of  the  latter  must  ever  extend  so  that  finally 
nothing  will  be  left  of  the  former,  which  will  have  become 
amalgamated  with  necessity.  We  shall  be  constrained  to 
beheve  more  and  more  in  a  supreme  law  that  will  be  a  com- 
plete expression  of  all  the  partial  laws  which  science  presents 
to  us  as  more  or  less  permanent  results  of  individual  researches. 

Our  conversation  was  centred  about  these  individual  laws, 
such  as  those  that  are  taught  in  the  theory  of  gases,  optics, 
etc.,  and  that  are  associated  with  the  names,  Boyle,  Gay- 
Lussac,  Dalton,  Mariotte,  Huyghens,  Fresnel,  Kirchhoff, 
Boltzmann,  and  others.  In  connexion  with  these  I  asked 
Einstein  whether  he  regarded  the  laws  as  things  unconditioned 
in  themselves,  and  capable  of  proof  under  every  set  of  circum- 
stances ;  and  whether  absolutely  valid  laws  existed  or  could 
exist. 

Einstein's  answer  was  essentially  in  the  negative.  **  A 
law  cannot  be  final,  if  only  for  the  reason  that  the  conceptions, 
which  we  use  to  formulate  it,  show  themselves  to  be  imperfect 
or  insufficient   as  science   progresses.     Let   us   consider,  for 

200 


DISCONNECTED  SUGGESTIONS  201 

example,  an  elementary  law  such  as  Newton's  Law  of  Force. 
From  our  more  recent  point  of  view  we  find  the  conception 
of  direct  action  at  a  distance  to  be  inexact  in  Nature.  For 
it  has  been  shown  that  action  at  a  distance  is  not  an  ultimate 
factor,  but  must  be  resolved  into  a  multiplicity  of  actions 
between  immediately  neighbouring  points  (The  Theory  of 
Action  by  Contact  or  Contiguous  Action).  Another  example 
is  provided  by  the  conception  Temperature.  This  conception 
becomes  meaningless  if  we  endeavour  to  apply  it  to  molecules  : 
it  leads  to  no  result  if  we  try  to  impose  it  on  the  smallest  parts 
of  matter  as  such.  The  reason  is  that  the  state,  the  velocity, 
and  the  inner  energy  of  the  individual  molecules  fluctuates 
between  very  wide  limits.  The  conception  *  temperature  ' 
is  applicable  only  to  a  configuration  composed  of  many  mole- 
cules, and  even  then  it  is  not  appUcable  quite  generally.  For 
let  us  picture  to  ourselves  an  extremely  rarefied  gas  contained 
in  a  closed  receiver.  Two  opposite  walls  are  to  be  at  different 
temperatures,  the  one  being  cold  and  the  other  being  hot 
In  a  gas  at  such  very  low  pressure  the  molecules  come  into 
colHsion  so  seldom  that,  practically,  we  have  to  take  into 
account  only  the  collisions  of  the  molecules  with  the  confining 
walls.  The  molecules  that  rebound  from  the  hot  wall  have 
greater  velocities  than  those  coming  from  the  colder  wall,  and 
hence  the  conception  of  temperature  becomes  untenable  for 
this  gas." 

**  Would  the  temperature-scale  on  the  thermometer  then 
denote  nothing  ?  "  I  asked.  **  The  greater  or  lesser  degree  of 
warmth  of  a  body,  in  this  case  of  the  mass  of  gas,  depends  on 
the  more  rapid  or  less  rapid  motion  of  its  smallest  parts.  The 
motions  are  in  any  case  present,  so  what  would  a  thermometer 
indicate  ?  " 

"  It  would  betray  only  that  it  had  nothing  to  indicate. 
If  a  thermometer  that  is  blackened  on  one  side  were  inserted 
into  the  vessel  containing  the  gas,  then  different  temperatures 
would  be  recorded  if  the  thermometer  were  gradually  turned 
about  its  own  axis  ;  and  this  signifies  that  the  conception  of 
temperature  has  become  meaningless  for  this  configuration 
of  molecules.  And  passing  beyond  the  quoted  examples,  I 
should  maintain  that  all  our  conceptions,  however  subtly  they 
may  have  been  thought  out,  are  shown  in  the  course  of  pro- 


202  EINSTEIN  THE  SEARCHER 

gressive  knowledge  to  be  too  rough  hewn,  that  is,  too  little 
differentiated/' 

We  spoke  of  the  "  Properties  of  Things,"  and  of  the  degree 
to  which  these  properties  could  be  investigated.  As  an 
extreme  thought,  the  following  question  was  proposed  : 

Supposing  it  were  possible  to  discover  all  the  properties 
of  a  grain  of  sand,  would  we  then  have  gained  a  complete 
knowledge  of  the  whole  universe  ?  Would  there  then  remain 
no  unsolved  component  of  our  comprehension  of  the  universe  ? 

Einstein  declared  that  this  question  was  to  be  answered 
with  an  unconditional  affirmative.  "  For  if  we  had  completely 
and  in  a  scientific  sense  learned  the  processes  in  the  grain  of 
sand,  this  would  have  been  possible  only  on  the  basis  of  an 
exact  knowledge  of  the  laws  of  mechanical  events  in  time  and 
space.  These  laws,  differential  equations,  would  be  the  most 
general  laws  of  the  universe,  from  which  the  quintessence  of  all 
other  events  would  have  to  be  deducible." 

[This  thought  may  be  spun  out  in  yet  another  direction. 
Every  piece  of  research,  however  specialized  it  may  appear 
and  of  whatever  minor  importance  it  may  be,  retains  a  relation- 
ship with  researches  into  the  universe,  and  may  prove  to  be 
valuable  for  this  latter  task.  If  we  accept  the  view  that 
science  is  capable  of  realizing  perfection,  then  every  con- 
tribution to  knowledge,  even  the  most  insignificant,  is  essenti- 
ally indispensable  for  attaining  this  goal.] 

Can  a  physical  law  alter  with  time  ?  In  more  precise 
language,  can  time,  as  such,  enter  explicitly  into  laws,  so  that, 
for  example,  an  experiment  that  is  carried  out  at  different 
times  leads  to  different  results  ?  This  question  has  been 
treated  several  times,  among  others,  by  Poincar6,  who  answered 
it  with  an  emphatic  "  No  !  "  but  also  by  others  to  whom  the 
invariability  of  physical  laws  did  not  seem  to  hold  for  all 
eternity.  If  my  memory  does  not  play  me  false,  Helmholtz 
once  expressed  faint  doubts  about  the  constancy  of  laws. 

Einstein  answered  this  question  with  a  decided  negative. 
**  For  a  law  of  physical  nature  is,  by  definition,  a  rule  to  which 
events  conform  wherever  and  whenever  they  take  place. 
Thus,  if  we  were  to  be  compelled  as  a  result  of  experience  to 


DISCONNECTED  SUGGESTIONS  208 

make  a  law  dependent  on  time,  it  would  be  a  necessary  step 
to  seek  a  law  independent  of  time,  which  would  include  in 
itself  the  law  dependent  on  the  time  as  a  special  case.  The 
latter  would  be  excluded  from  the  category  of  physical  laws, 
and  would  henceforward  play  the  part  only  of  a  result  deduced 
from  the  law  which  is  independent  of  the  time/* 

What  attitude  should  we  adopt  if,  in  studying  a  scientific 
doctrine,  we  encounter  paradoxical  results  even  though  the 
inferences  have  been  drawn  correctly — ^that  is,  if  we  meet 
with  a  deduction  to  which  our  reasoning  powers  object, 
although  no  fallacy  is  discoverable  in  the  argument  ? 

Before  we  deal  with  cases  which  seem  to  me,  personally, 
to  be  interesting,  let  us  hear  what  is  Einstein's  attitude  in 
general.  "  As  soon  as  a  paradox  presents  itself,  we  may,  as  a 
rule,  infer  that  inaccurate  reasoning  is  the  cause,  and  should 
thus  examine  in  each  particular  case  whether  an^^errorlof 
logic  is  discoverable,  or  whether  the  paradoxical  result  denotes 
only  a  violent  contrast  with  our  present  views.*' 

Let  us  first  take  examples  from  an  entirely  modem  science, 
from  the  Theory  of  Aggregates  founded  by  Georg  Cantor  of 
Halle.  We  shall  follow  the  argument  by  the  only  possible 
method  for  this  book,  namely,  by  rough  indications  that  will 
serve  our  purpose  and  do  not  claim  to  be  accurate  in  expression 
or  in  sense. 

If  we  take  an  aggregate  of  three  objects,  for  example,  an 
apple,  a  pear,  and  a  plum,  we  may,  by  definition,  form  six 
partial  aggregates,  namely : 

the  apple 
the  peax 
the  plum 


UlC     piUIU 

the  apple  and  the  pear 
the  apple  and  the  plum 
the  pear  and  the  plum. 


The  aggregate  of  the  partial  aggregates,  which  contains 
six  elements,  is  thus  greater  than  (actually  twice  as  great 
as)  the  original  aggregate,  in  which  only  three  elements 
occur. 

If  the  original  aggregate  contains  an  additional  element, 


204  EINSTEIN  THE  SEARCHER 

for  example,  a  nut,  the  following  partial  aggregates  may  be 
formed  : 

the  apple 

the  peax 

the  plum 

the  nut 

the  apple  and  the  pear 

the  apple  and  the  plum 

the  apple  and  the  nut 

the  pear  and  the  plum 

the  pear  and  the  nut 

the  plum  and  the  nut 

the  apple,  the  pear,  and  the  plum 

the  apple,  the  pear,  and  the  nut 

the  apple,  the  plum,  and  the  nut 

the  pear,  the  plum,  and  the  nut. 

Thus,  in  this  case,  the  aggregate  of  the  partial  aggregates  is 
already  considerably  greater  than  the  original  aggregate.  This 
numerical  excess  increases  rapidly  with  each  successive  increase 
in  the  original  aggregate,  so  that  if  we  apply  the  same  reason- 
ing to  an  infinite  aggregate,  the  aggregate  of  partial  aggregates 
becomes  an  infinity  of  a  higher  order.  This  is  expressed  by 
sa5dng  that  the  infinite  aggregate  of  partial  aggregates  has  a 
greater  potentiality  than  the  infinity  of  the  elements  of  the 
original  aggregate. 

So  we  see  that  the  one  infinity  is,  in  popular  language, 
much  more  comprehensive,  more  powerful  than  the  other. 
Our  minds  do  not  find  it  impossible  to  grasp  this.  But  in  a 
definite  imaginary  experiment  it  is  found  that  this  theorem 
of  progression  not  only  fails  in  its  application,  but  leads  to 
flagrant  contradiction. 

For  if  we  start  from  the  primary  aggregate  of  "  all  con- 
ceivable things,'*  its  infinity  can  certainly  not  be  transcended 
by  any  other  infinity.  But  according  to  the  above  theorem 
the  "  aggregate  of  all  partial  aggregates  "  would  have  a  greater 
potentiality,  although  it  itself  cannot  extend  further  than 
to  the  conception  of  the  maximum  of  all  conceivable  things. 
We  thus  arrive  at  an  insoluble  paradox,  a  typical  example  of 
how,  in  the  system  of  conceptions  involved,  something  is 
insufficient  or  not  in  conformity  with  logical  thought.  And 
this  sceptical  view  receives  support  from  various  remarks  of 
Descartes,  Locke,  Leibniz,  and  particularly  Gauss,  who,  long 


DISCONNECTED  SUGGESTIONS  205 

before  the  advent  of  the  Theory  of  Aggregates,  raised  a  protest 
against  inexact  definitions  of  infinity. 

In  another  case,  however,  the  same  theory  seems  to  arise 
by  perfectly  logical  processes,  although  it  again  leads  to  a 
statement  that  does  not  seem  correct  to  "  common  sense." 
For  it  shows  by  a  very  subtle  and  ingenious  method  that  all 
the  surface-points  of  a  surface  infinitely  extended  in  all  direc- 
tions may  be  brought  to  correspond  in  a  reversible  single 
manner  to  the  linear  points  of  a  Une,  however  small ;  so  that 
to  every  point  of  the  unhmited  plane  there  corresponds  a 
definite  point  of  the  fine,  and  vice  versa.  The  same  theorem 
may  be  extended  to  three-dimensional  space,  with  the  result 
that  we  have  to  reconcile  ourselves  with  the  incredible  fact 
that,  expressed  in  popular  language,  a  straight  line  of  however 
small  length  exhibits  the  same  potentiality  with  regard  to  the 
number  of  its  points,  as  all  the  points  in  the  universe. 

For  my  own  part,  I  must  confess  that  no  means  suggests 
itself  to  me  to  make  this  paradox  intelligible.  But  the  sacri- 
ficium  intellectus  comes  within  dangerous  proximity.  Einstein, 
who  values  and  marvels  at  the  theory  of  aggregates  as  a  science, 
or  perhaps  more  as  a  work  of  art  built  up  from  the  materials  of 
science,  gives  whole-hearted  support  to  the  proof.  He  refuses 
to  accept  the  notion  of  a  paradox — ^that  is,  he  recognizes  a 
contradiction  not  in  our  process  of  reasoning,  but  only  in  a 
habit  of  thought  that  is  open  to  correction.  I  should  give 
much  to  discover  the  means  of  correction  ! 

A  third  example  arises  out  of  the  special  theory  of  rela- 
tivity. It  has  a  mysterious  paradoxical  character  that 
vanishes  when  a  clear  view  of  the  relationships  involved  has 
been  obtained. 

According  to  this  theory  the  rate  at  which  events  happen 
alters  according  to  the  state  of  motion  of  the  system  under 
consideration.  Let  us  now  consider  two  twins  A  and  B, 
that,  although  born  at  one  place  on  the  earth,  are  immediately 
separated,  B  remaining  at  rest,  whilst  A  rushes  out  into  space 
at  an  enormous  rate,  describing  what,  viewed  from  the  earth, 
is  an  inconceivably  great  circle.  In  this  way  the  rate  of 
happening  of  all  events  is  reduced  very  considerably  for  A 
in  a  manner  that  may  be  calculated.     If  A  then  returns  to 


206  EINSTEIN  THE  SEARCHER 

B,  it  may  happen  that  the  twin  who  stayed  at  home  is  now 
sixty  years  old,  whereas  the  wanderer  is  only  fifteen  years  of 
age,  or  is  perhaps  only  an  infant  still. 

The  first  introduction  to  this  flight  of  imagination  naturally 
causes  profound  perplexity.  Nevertheless,  we  are  dealing  not 
with  a  realm  of  miracles,  but  with  something  that  is  within 
the  range  of  comprehension. 

"  In  the  case  of  these  two  twins,"  Einstein  declared,  "  we 
have  merely  a  paradox  of  feeling.  It  would  be  a  paradox  of 
thought  only  if  no  sufficient  ground  could  be  suggested  for  the 
behaviour  of  these  two  creatures .  This  ground,  which  accounts 
for  the  comparative  youth  of  A,  is  given,  from  the  point  of 
view  of  the  special  theory  of  relativity,  by  the  fact  that  the 
creature  in  question,  and  only  this  creature,  has  been  subject 
to  accelerations.  A  proper  grasp  of  the  reason  is  furnished 
only  when  we  adopt  the  general  theory  of  relativity,  which 
tell  us  that,  from  the  point  of  view  of  A,  a  centrifugal  field 
exists,  whereas  it  is  absent  from  the  point  of  view  of  B.  This 
field  exerts  an  influence  on  the  relative  rate  of  happening  of 
the  events  of  life.*' 

It  certainly  requires  a  prodigious  mechanism  to  allow 
the  moving  twin  to  gain  even  only  one  second  of  time.  If  he 
were  to  spend  a  year  in  a  merry-go-round  whose  circumference 
were  about  19  milliard  miles  in  length,  he  would  have  to 
travel  in  it  at  the  rate  of  over  600  miles  per  second  if  he  is  to 
gain  a  second  on  his  brother. 

This  inevitable  result  that  is  immediately  apparent  to  a 
trained  scientific  mind  throws  light  on  the  nature  of  "  common 
sense,''  the  validity  of  which,  as  an  ultimate  criterion,  Kant 
too  has  refused  to  recognize,  in  so  far  as  this  "  common  sense  " 
is  incapable  of  passing  beyond  the  examples  offered  in  its  own 
experience.  It  circulates,  as  Einstein  says,  in  the  "  realms 
of  feeling  and  analogy.''  It  finds  no  analogy  for  a  phenomenon 
like  that  described  above,  and  since  it  can  apply  rules  only 
concretely,  many  things  appear  to  it  paradoxical  that,  in  the 
light  of  intensified  abstraction,  appear  logical  and  necessary. 

Let  us  speculate  on  the  following  question.  If  all  things 
in  the  universe  should  increase  or  decrease  enormously  in 
dimensions,  and  if,  at  the  same  time,  in  a  manner  totally 


DISCONNECTED  SUGGESTIONS  207 

concealed  from  us,  certain  physical  conditions  should  become 
changed,  we  should  lack  all  means  of  discovering  the  difference 
between  things  before  and  after  the  change.  For  since  all 
measuring-rods,  including  those  furnished  by  our  senses,  would 
have  become  changed  in  the  same  proportion,  the  two  condi- 
tions could  not  be  differentiated  from  one  another.  It  may 
easily  be  shown  that  this  would  necessarily  occur,  if  an  extra- 
mundane  power  were  non-uniformly  to  displace,  deform, 
compress,  or  bend  all  things  in  the  universe,  provided  that  our 
instruments  and  senses  participated  in  this  transformation. 
Accordingly  it  is  permissible  also  to  regard  the  universe  known 
to  us  as  one  that  is  deformed,  and  one  that  is  derived  from 
another,  the  original  form  of  which  will  ever  remain  a  secret 
to  us. 

Is  there  any  connexion  between  this  grotesque  speculation 
and  the  theory  of  relativity  ? 

We  can  establish  only  one  that  is  negative  and  that  arises 
e  contrario,  "  These  deformations,"  said  Einstein,  "  are  in 
themselves  abstractions  that  are  physically  meaningless.  Only 
relations  between  bodies  have  a  physical  meaning,  for  example, 
the  relation  between  measuring-rods  and  the  objects  they 
measure.  Therefore,  it  is  reasonable  to  talk  of  deformations 
only  when  we  are  dealing  with  the  deformations  of  two  or 
more  bodies  with  respect  to  one  another,  whereas  the  con- 
ception of  deformation  has  no  sense,  unless  a  real  object  is 
specified,  to  which  it  is  referred.  The  philosophical  merit  of 
the  general  theory  of  relativity,  as  compared  with  previous 
views  of  physics,  consists  in  the  fact  that  the  former  avoids 
entirely  these  meaningless  abstractions  with  respect  to  space 
and  time." 

[According  to  this,  it  is  not  purposeless  to  enter  on  these 
grotesque  trains  of  thought,  even  if  they  are  untenable  physi- 
cally. For  since  the  new  physics  teaches  us  to  avoid  these 
false  tracks,  it  seems  of  value  to  know  what  it  is  that  is  to  be 
avoided.  Just  as  we  must  study  scholastic  thought  if  we 
wish  to  grasp  thoroughly  the  philosophy  which  sprang  up  after 
the  scholastic  fetters  were  burst.  Moreover,  these  reflections 
on  concealed  universes  are  not  without  a  certain  attraction, 
reminiscent  of  the  sorcerer's  wand,  if  they  pursued  any  other 
goal  than  that  of  making  universes  distorted.    It  is  true  that 


208  EINSTEIN  THE  SEARCHER 

they  hold  out  latent  temptations  that  may  in  some  cases  lead 
us  on  to  dangerous  ground,  in  encouraging  us  to  venture  on 
analogies  beyond  the  scope  of  geometry  and  physics.  Would 
it  be  possible  to  enter  suddenly  into  a  world  that  is  distorted 
and  deformed  with  respect  to  its  ethics,  its  culture,  and  its 
reasoning  intellects,  without  our  observing  the  difference  ? 
Are  we  ourselves  perhaps  living  under  such  deranged  conditions, 
of  which  we  cannot  become  aware,  because  our  perceptual 
organs  have  likewise  become  deformed  ?  I  must  frankly 
confess  that  I  do  not  regard  it  as  quite  inconceivable  that 
this  argument  of  deformation  may  be  spun  out  in  this  direction, 
but  I  must  add  that  Einstein  rejects  absolutely  all  such  exten- 
sions, since,  as  he  emphasizes,  they  lead  to  regions  that  are 
merely  fields  for  the  exhibition  of  "  verbal  gymnastics/*] 

The  question  whether  Nature  makes  leaps  or  not  is  very 
old.  In  the  theory  of  descent  it  forms  the  foundation  of  the 
difference  between  revolutionists  and  the  evolutionists,  who 
uphold  the  axiom  natura  non  facit  saltus,  with  all  its  conse- 
quences. Recently  attempts  have  been  made,  particularly  by 
psychologists,  to  propound  and  justify  a  natural  principle  of 
discontinuity.  They  assert  that  our  own  perceptions  and 
sensations  are  discontinuous  in  themselves,  and  that  the 
mechanism  of  every  perception  is  akin  to  that  of  a  cinemato- 
graph with  its  extremely  rapid  interruptions.  If  this  should 
actually  be  the  case,  we  should  scarcely  have  a  means  of  solving 
definitely  the  question  whether  continuity  reigns,  or  not,  in 
Nature. 

Einstein  does  not  recognize  the  possibility  of  this  alternative 
for  a  moment.  If  a  doubt  had  ever  arisen,  the  researches  of 
Maxwell  would  in  themselves  have  been  sufficient  to  dispel  it. 
Our  universe  that  is  to  be  described  in  terms  of  differential 
equations  is  absolutely  continuous. 

"  But,"  I  interjected,  "  does  not  modern  physics  offer  a 
certain  support  to  the  assumption  of  a  discontinuity  ?  Does 
not  the  Quantum  Theory  point  to  an  atomistic  structure  of 
energy,  and  hence  also  of  events  that  are  to  be  imagined  as 
happening  in  jerks  and  as  involving  relations  expressible  in 
whole  numbers  ?  *' 

Einstein  gave  an  answer  of  epigrammatic  brevity  and 


DISCONNECTED  SUGGESTIONS  209 

flavour.  "  The  fact  that  these  phenomena  are  expressible  in 
whole  numbers  must  not  be  construed  into  an  argument 
against  continuous  happening.  Just  imagine  to  yourself  for 
a  moment  that  beer  is  sold  only  in  whole  litres  ;  would  you 
then  infer  that  beer,  as  such,  is  discontinuous  ?  " 

What  achievements  are  to  be  expected  of  astronomy  in  the 
present  era  ? 

This  question  would  have  a  special  meaning  if  it  were 
assumed  that  the  astronomer  who  works  in  observatories  is 
surrounded  by  solved  problems,  and  can  no  longer  hope  to 
solve  problems  having  the  universal  significance  of  those  of 
Coperniciis  or  Kepler.  This  assumption,  however,  would  not 
be  in  agreement  with  the  actual  state  of  affairs. 

Einstein  indicated  to  me  a  number  of  fundamental  prob- 
lems that  present  themselves  to  modem  astronomy,  and  the 
solution  of  which  he  expected  of  future  times. 

Above  all,  the  geometrical  and  physical  constitution  of  the 
stellar  systems  will,  in  the  main,  become  revealed. 

At  present  we  do  not  yet  know  whether  Newton's  Law  of 
Attraction  holds,  at  least  approximately,  for  configurations  of 
the  type  of  the  Milky  Way  and  of  the  spherical  clusters  of 
stars — ^that  is,  in  extents  of  space  in  which  the  influence  of 
space-curvature  would  become  appreciable.  The  rapid  pro- 
gress of  recent  astronomy  justifies  our  great  hopes  that  the 
solution  of  this  universal  problem  will  be  found  within  the 
coming  decades. 

In  distant  connexion  with  this  we  also  touched  on  the 
question  of  the  habit  ability  of  other  worlds.  This  theme  of 
Fontenelle,  "  la  pluralite  des  mondes  habits,"  which  has 
again  become  a  centre  of  public  interest,  owing  to  investigations 
of  Mars,  has  evoked  a  storm  of  discussion.  We  hear  the  noisy 
war-cries  of  geocentric  scientists  who  wish  to  regain  for  the 
earth  her  shattered  supremacy  in  astronomy,  and  who  claim 
the  existence  of  organic  forms  as  the  sole  prerogative  of  our 
planet.  It  is  scarcely  necessary  to  mention  that  Einstein 
rejects  the  motives  of  these  human  and  all-too-human  in- 
dividuals as  small-minded  and  short-sighted.  Creatures  in 
distant  worlds  are  derived  from,  and  are  subject  to,  conditions 
of  organic  nature,  of  which  we  can  form  no  idea  by  deductions 
14 


210  EINSTEIN  THE  SEARCHER 

from  the  world  which  we  inhabit.  But  to  deny  their  existence 
on  numberless  constellations,  or  to  demand  an  ocular  proof 
of  their  presence,  is  no  better  than  to  assume  the  point  of  view 
of  an  infusoria  to  whom  there  is  no  life  other  than  that  in  a 
dirty  drop  of  ditch-water. 

The  idea  of  the  atom  as  the  ultimate  structural  element 
involves  a  philological  as  well  as  a  conceptual  contradiction. 
For  atomos  signifies  the  indivisible,  the  no-further-divisible, 
whereas  the  idea  of  a  body,  however  small,  an  element  of 
structure  differing  from  zero,  demands,  at  least  geometrically, 
further  divisibility.  Even  the  original  founders  of  the  theory 
of  atoms,  Leukippus,  Epicurus,  and  Democritus,  assigned 
definite  forms  to  the  ultimate  components,  and  we  may  read 
in  the  splendid  work  of  Lucretius  how  he  infers  from  the 
nature  of  substance  that  the  ultimate  particles  are  smooth, 
round,  or  rough,  or  have  the  shapes  of  hooks  and  eyes.  The 
further  analysis  pressed  forward,  the  more  the  simplicity  of  the 
original  idea  vanished.  Microcosms  came  to  be  regarded  as 
copies  of  macrocosms,  and  the  atoms  of  present-day  science 
actually  exact  from  us  that  we  should  regard  them  as  worlds 
in  themselves. 

Einstein  acceded  to  my  request  that  he  might  give  a  sketch 
of  the  latest  achievements  of  science  sufficient  to  provide  an 
approximate  idea  of  the  atomic  model.  According  to  the 
researches  of  Rutherford  and  Niels  Bohr,  we  are  to  picture  it 
as  a  planetary  system. 

The  central  body  of  this  system  is  represented  by  a  positively 
charged  nucleus,  which  constitutes  almost  the  whole  mass  of 
the  atom,  surrounded  by  a  certain  number  of  electrons,  negative 
charges,  that  move  in  uniform  circular  or  elliptic  orbits  about 
the  nucleus.  There  is  thus  a  certain  analogy  that  allows  us 
to  regard  the  nucleus  as  the  sun,  and  the  electrons  as  the 
planets  of  this  system. 

The  number  of  these  electrons  varies  between  the  limits 
T  and  92,  according  to  the  chemical  constitution  of  the  element. 
The  smallest  number  occurs  in  the  case  of  helium  (in  which 
there  are  two),  and  of  the  hydrogen  atom,  in  which  only  one 
electron-planet  describes  its  circular  path  about  the  nucleus. 
In  other  atoms  there  are  probably  more  comphcated  orbits, 


DISCONNECTED  SUGGESTIONS  211 

although  they  are  more  or  less  approximately  circular.  Ac- 
cording to  this  still  very  new  theory,  which  is  supported  by 
very  convincing  facts,  the  electrons  are  to  be  imagined  as 
arranged  in  concentric  sheUs  (like  the  layers  of  an  onion), 
among  which  the  innermost  shell  plays  a  distinctive  part 
inasmuch  as  the  number  of  the  electrons  arranged  in  it  decides 
the  chemical  character  of  the  atom  in  question.  It  sometimes 
occurs  that  electrons  spring,  under  external  influence,  from  one 
orbit  to  another  ;  when  the  electron  jumps  back  to  the  original 
orbit,  Ught  is  emitted.  An  essential  fact  is  to  be  noted : 
Whereas  any  arbitrary  orbits  of  any  arbitrary  radius  may 
occur  in  a  planetary  system  of  the  celestial  regions,  the  mani- 
fold of  these  orbits  in  the  case  of  the  electrons  is  restricted, 
in  that  only  certain  orbits  are  possible,  namely,  those  that  are 
determined  mathematically  by  the  quantum  condition. 

*'  Perhaps,'*  I  interrupted,  "  the  whole  analogy  may  be 
inverted.  If  the  atom  is  considered  analogous  to  a  planetary 
system  in  the  model,  it  should  be  admissible  to  regard  our 
true  planetary  system  as  a  cosmic  atom.  And  then,  long  after 
we  have  become  accustomed  to  regard  our  earth  as  playing  the 
part  of  a  grain  of  sand,  the  sovereignty  of  the  sun,  too,  would 
be  past.  The  whole  majesty  of  the  solar  system  as  far  as  the 
orbit  of  Neptune  would  then  shrink  to  a  configuration  com- 
pared with  which  the  world  of  a  grain  of  sand  would  be 
infinitely  complex." 

"  This  fantastic  inversion  is  permissible  up  to  a  certain 
extent,"  said  Einstein,  "  but  we  must  not  lose  sight  of  the 
fact  that  there  is  a  cardinal  difference.  If  we  disregard  the 
enormous  disparity  in  dimensions,  the  analogy  is  far  from 
exact  owing  to  the  circumstance  that  the  atom  is  only  an 
element  of  structure,  whereas  the  true  planetary  system  is  an 
extraordinarily  complex  structure  in  itself.  Thus  the  differ- 
ence between  a  simple  thing  and  one  that  is  very  highly 
complex  still  remains." 

**  But,  Professor,  may  not  a  similar  complexity  yet  be 
discovered  in  the  atom  ?  It  may  be  merely  a  difference  of 
philosophical  view  from  the  primary  idea  to  that  of  regarding 
the  electrons  as  circulating  Hke  planets.  May  we  not  con- 
jecture that  in  each  successive  step  we  are  merely  carrying  out 
a  true  regressus  in  infinitum  ?  " 


212  EINSTEIN  THE  SEARCHER 

"  That  seems  highly  improbable,"  he  replied,  "  although, 
of  course,  structural  investigations  can  never  cease.  At  first 
they  are  directed  at  the  more  remote  object  of  finding  out  why 
certain  atoms  are  radioactive,  that  is,  exhibit  a  tendency  to 
disintegrate.  It  has  already  been  established  that  this  ten- 
dency is  a  property  of  the  positive  nucleus,  of  which  Uttle  is  as 
yet  known.  This  means  that  the  nucleus  is  not  simple,  yet 
it  does  not  open  up  the  possibility  of  an  unending  regression. 
Our  aim  must  be  to  get  a  clear  insight  into  the  constitution 
of  the  nucleus,  as  regards  the  positive  and  negative  charges, 
and  it  is  my  opinion,"  he  concluded,  "  that  beyond  this  there 
will  be  no  further  subdivision  of  matter." 

When  Goethe  writes  of  the  immovable  pole  in  the  flux  of 
phenomena,  we  recognize  that  his  beautiful  remark  pronounces 
an  elegy  to  the  possibility  of  attaining  ultimate  simplicity. 
Einstein's  utterance,  if  I  understand  him  aright,  converts  this 
elegy  into  a  song  of  hope.  If  the  subdivision  of  matter 
actually  has  an  end  somewhere,  then  we  are  now  on  the 
threshold  of  ultimate  things,  we  are  near  the  immovable  pole, 
which  we  are  capable  of  reaching. 


"  Every  new  truth  of  science  must  be  such  that,  in  ordinary 
writing,  it  may  be  communicated  completely  within  the  space 
of  a  quarto  leaf."  Kirchhoff  made  this  remark,  and  gave  a 
sufficient,  if  not  literal,  demonstration  of  its  truth.  When 
Bunsen  and  he  published  the  first  notice  about  spectral 
analysis,  they  compressed  their  publication  into  the  small 
space  of  three  printed  pages. 

But  what  is  to  happen  if  the  new  truth  should  be  built 
up  of  very  comprehensive  materials,  when  it  requires  many 
links,  of  which  none  can  be  omitted  if  the  truth  is  to  be 
made  intelligible  ?  Would  Kirchhoff *s  quarto  page  still  be 
sufficient  ? 

"  Certainly,"  said  Einstein,  '*  provided,  of  course,  that  it  is 
addressed  to  a  reader  who  has  already  mastered  what  went 
before — ^that  is,  to  one  who  is  so  far  acquainted  with  the  older 
facts  that  he  has  to  learn  only  the  really  new  part  of  the  new 
truth." 

*'  That  sounds  very  hopeful,"  I  remarked,  **  for  then  it 


DISCONNECTED  SUGGESTIONS  213 

should  also  be  possible  to  describe  very  briefly  the  theory  of 
relativity/* 

"  Let  us  rather  say  its  essentials — ^the  heart  of  the  matter. 
Well,  then,  get  your  Kirchhoff  page  ready.  We  shall  see 
whether  we  can  set  out  on  it  the  special  theory  of  relativity." 

The  totaUty  of  our  experience  compels  us  to  assume  that 
Ught  travels  with  a  constant  velocity  in  empty  space.  like- 
wise, our  whole  experience  in  optics  compels  us  to  recognize 
that  all  inertial  systems  are  equivalent ;  these  are  systems 
that  are  produced  from  an  allowable  one  by  means  of  a  uniform 
translation.  An  allowable  system  is  one  in  which  GaUlei's 
and  Newton's  Law  of  Inertia  holds.  (This  law  states  that  a 
moving  body  that  is  left  to  itself  retains  its  direction  and 
velocity  permanently.) 

Now,  the  law  of  the  constancy  of  light  propagation  seems 
to  conflict  with  the  classical  principle  of  relativity,  according 
to  which  the  velocity  of  a  ray  of  Ught  assumes  different  values 
in  the  moving  system  according  to  the  direction  of  the  ray. 

This  apparent  incompatibiHty  arises  from  the  following 
unproved  assumptions  : 

(a)  If  two  events  are  simultaneous  with  regard  to  one 
inertial  system,  they  are  also  simultaneous  with  regard  to 
any  other  inertial  system. 

(b)  The  length  of  a  measuring-rod,  the  shape  smd  size  of  a 
rigid  body,  and  the  rate  of  a  clock  are  independent  of  their 
motion  with  respect  to  the  system  of  reference  used,  provided 
this  motion  is  rectilinear  and  non-rotational. 

These  assumptions  must  be  discarded  if  this  disagreement 
is  to  be  ehminated.  If  we  substitute  for  them  the  assumption 
that  all  inertial  systems  are  equivalent  and  that  the  velocity 
of  light  in  vacuo  is  constant,  we  ^et  : 

(i)  That  the  dimensions  of  bodies  and  the  rate  of  clocks 
have  a  functional  relation  to  the  motion. 

(2)  That  the  equations  of  motion  of  Newton  require  to 
be  modified  ;  this  modification  leads  to  results  that,  for  rapid 
motions,  differ  appreciably  from  those  of  Newton. 

This  is,  in  a  very  compressed  form,  the  meaning  of  the 
special  theory  of  relativity. 

As  there  is  still  some  space  left  on  our  quarto  page,  we 


214  EINSTEIN  THE  SEARCHER 

may  add  k  remark  that,  it  is  hoped,  will  make  a  little  clearer 
the  above-mentioned  discrepancy. 

Let  us  choose  as  our  system  of  reference  an  express  train 
i8  miles  long.  There  are  two  passengers — Mr.  Front,  right  at 
the  front  of  the  train,  and  Mr.  Back,  at  the  extreme  end  of  the 
train,  so  that  a  rigid  distance  of  i8  miles  separates  the  two 
passengers.  The  carriages  are  transparent,  so  that  the  two 
passengers  can  signal  to  one  another.  They  are,  moreover, 
furnished  with  ideal  clocks  that  run  at  exactly  the  same  rate. 

First,  suppose  that  the  train  is  at  rest .  Back  is  just  opposite 
milestone  lOO,  whilst  Front  is  opposite  milestone  ii8.  By 
means  of  a  flash,  Back  signals  to  Front  his  time,  exactly 
12  o'clock.  It  takes  light  very  nearly  ytt.^otj-  second  to 
traverse  the  length  of  the  train — 18  miles  ;  hence  the  flash  will 
reach  Front  at  12  o'clock  tt^.^tht  second.  Exactly  the  same 
result  would  have  come  about  if  Front  had  signalled  his  time 
to  Back.  Light  makes  no  difference  in  travelling  forwards 
and  backwards.  If  the  train  moves  at  a  great  speed,  the  two 
travellers  can  conduct  the  same  experiment  as  when  the  train 
was  at  rest.  They  will  then  set  the  time  that  light  takes  to 
travel  from  Back  to  Front  equal  to  the  time  that  it  takes  to 
traverse  the  same  way  in  the  reverse  direction.  But  this 
phenomenon  will  assume  a  different  aspect  if  viewed  from  the 
railway  embankment.  An  observer  on  the  latter  would 
aihrm  that  Hght  does  not  take  the  same  time  in  travelHng  the 
length  of  the  train  in  one  direction  as  it  does  when  travelling 
in  the  opposite  direction. 

For  the  ray  of  light  moving  in  the  forward  direction  has 
to  traverse  not  only  the  distance  between  Back  and  Front, 
but  also  the  very  short  distance  that  Front  has  moved  forward 
during  the  interval  that  the  light  has  been  moving  ;  whereas, 
inversely,  the  flash  sent  out  by  Front  to  Back  will  traverse 
a  distance  that  is  correspondingly  less  than  that  between  the 
passengers,  since  Back  is  moving  towards  the  signal. 

Thus  the  duration  of  the  two  phenomena  of  light  propaga- 
tion is  the  same  or  different,  respectively,  according  as  it  is 
judged  from  the  train  or  from  the  embankment.  In  other 
words,  the  judgment  of  the  length  of  time  depends  on  the  state  of 
motion  of  the  observer. 

All  further  pronouncements  of  the  special  theory  of  rela- 


DISCONNECTED  SUGGESTIONS  215 

tivity  are  based  on  the  preceding  arguments  of  the  relativity 
of  time. 

Would  Man  be  able  to  construct  a  Science  if  he  possessed 
one  sense  less  than  at  present — ^for  example,  if  he  were  deprived 
of  sight  ?  Let  us  apply  this  to  a  definite  case.  In  the  new 
physics  the  velocity  of  light  plays  a  decisive  part  as  a  world- 
constant.  At  first  sight  it  would  appear  impossible  for  us 
to  determine  it  and  recognize  its  importance,  if  we  had  not  at 
our  disposal  some  organ  which  enabled  us  to  become  aware  of 
optical  phenomena. 

But,  as  Einstein  explained  to  me,  even  under  such  difiicult 
circumstances,  it  would  be  possible  to  build  up  a  science,  for 
the  reason  that  phenomena,  as  far  as  they  are  perceptible, 
may  be  transformed  so  that  they  become  manifest  to  other 
senses  if  one  sense  should  be  absent.  For  example,  the 
electrical  conductivity  of  selenium  is  strongly  influenced  by  the 
amount  of  illumination  that  falls  on  it.  Thus  Ught  acts  on  a 
selenium  cell,  causing  changes  of  current  intensity,  which  in 
their  turn  may  be  perceived  by  feeling,  or  by  chemical  action 
on  the  mucous  fluid  of  the  tongue.  Ultimately  we  are  con- 
cerned only  with  a  differentiation  that  enables  us  to  refer 
identical  experiences  to  identical  events.  We  should  certainly 
encounter  enormous  difiiculties  in  endeavouring  to  form  a 
physical  picture  of  our  surrounding  world  if  the  number  of  our 
senses  should  become  less  than  the  organs  with  which  we  actu- 
ally operate.  Yet,  in  principle,  we  should  be  able  to  overcome 
all  difficulties  by  means  of  much  lengthened  and  complicated 
lines  of  research,  even  if  we  should  have  only  a  single  sense 
left,  or  if  we  had  only  one  at  the  very  outset .  The  construction 
of  a  Science  would  then  be  possible,  and  would  give  the  same 
results,  although  it  might  be  propounded  only  after  a  delay  of 
perhaps  millions  of  years. 

[It  is  naturally  assumed  that  the  intellect  is  retained,  as 
this  is  the  necessary  condition  for  all  scientific  research.  Since 
the  degree  of  understanding  depends  on  the  senses — nihil  est 
in  intellectu,  quod  non  priusfuerit  in  sensu — ^we  may  conjecture 
that  a  human  being  with  only  one  sense  organ  would  work 
with  a  minimum  degree  of  understanding,  which  would  be 
insufficient  for  the  acquirement  of  any  knowledge  whatsoever. 


216  EINSTEIN  THE  SEARCHER 

This  transcendental  question,  which  lies  almost  beyond  the 
bounds  of  discussion,  was  not  touched  on  in  our  conversation, 
as  the  subject  was  restricted  so  that  it  should  not  drift  into 
metaphysical  regions. 

Nevertheless,  I  should  like  to  mention  that  a  speculation 
of  this  kind  is  recorded  in  the  history  of  science.  Condillac, 
in  a  study  teeming  with  ideas,  investigates  the  behaviour  of 
a  "  Statue,"  that  he  represents  as  a  human  being,  with  the 
assumption  that  there  is  at  first  no  idea  in  the  soul  of  this 
statue-person.  This  living  creature  is  enclosed  in  a  marble 
envelope,  the  sole  exterior  organ  of  which  is  at  first  the  organ 
of  smell.  He  then  shows  that  by  means  of  this  single  sense 
all  manner  of  sensations  and  expressions  of  will  may  develop 
in  his  "  statue."  Condillac  does  not,  however,  undertake  to 
give  a  convincing  proof  that  this  creature,  restricted  to  the 
organ  of  smell,  would  be  able  to  discover  physically  the  relation- 
ships that  hold  in  physical  nature,  and  thus  to  build  up  a 
scientific  sj^tem.  Thus  Einstein,  in  his  discussion,  goes 
considerably  further  than  the  author  of  this  statue.] 

Has  the  "  eternal  repetition,"  as  outlined  by  Nietzsche, 
any  meaning  ? 

The  sage  of  Sils -Maria  tells  us  that  this  revelation  came 
to  him  midway  between  tears  and  ecstasy,  as  a  fantasy 
with  a  real  meaning.  The  crux  of  his  idea  is  a  finite  world 
built  up  of  a  finite  number  of  atoms.  From  the  fact  that  the 
present  state  emerges  out  of  the  immediately  preceding  one, 
the  latter  from  the  one  just  before,  and  so  on,  he  concludes 
that  the  present  state  exhibits  repetition  both  forwards  and 
backwards.  All  becoming  recurs  and  moves  in  a  multiple 
cycle  of  absolutely  identical  states. 

Let  us  discard  for  the  moment  all  philosophical  objections, 
above  all  this,  that  the  recurrence  of  the  same  disposition 
of  atoms  may  not  necessarily  entail  the  recurrence  of  the 
same  psychical  states.  Furthermore,  let  us  suppress  the 
C5mical  thought  that  in  the  return  to  the  same  state  the  world 
would  have  reason  to  enjoy  extreme  happiness  only  for 
moments,  but  to  lament  for  aeons.  Then  we  are  left  with  the 
comparatively  simple  question  :  Is  this  repetition,  from  the 
point  of  view  of  physics,  conceivable  and  possible  ? 


DISCONNECTED  SUGGESTIONS  217 

It  would  be  the  death-knell  of  Nietzsche's  idea  if  the  answer 
of  a  great  physical  research  scientist  were  entirely  in  the 
negative.  But  Einstein  still  allows  it  a  small  measure  of  life. 
**  Eternal  repetition,"  so  he  expressed  himself,  "  cannot  be 
denied  by  science  with  absolute  certainty."  The  disciples  of 
Nietzsche  will  have  to  rest  satisfied  with  this  very  small  con- 
cession. For  what,  in  Nietzsche's  eyes,  is  a  logical  necessity 
becomes  transformed  by  Einstein's  supplementary  remark 
into  a  vague  assumption,  the  product  of  fantasy.  From 
the  point  of  view  of  physics  the  recurrence  of  the  same  con- 
dition is  to  be  regarded  as  "enormously  improbable."  This 
statement  is  founded  chiefly  on  the  famous  second  Law  of 
Thermodynamics,  according  to  which  the  processes  of  Nature 
are  in  the  main  irreversible,  so  that  a  one-sided  tendency  is 
expressed  in  natural  phenomena.  The  fact  that  the  course 
of  phenomena  is  in  only  one  sense  or  direction  speaks  in 
favour  of  the  view  that  the  events  of  the  world  are  to  be  re- 
garded as  occurring  only  once. 

So  that  when  Nietzsche,  in  contradistinction  to  this, 
vigorously  supported  the  doctrine  of  repetition,  he  contra- 
dicted at  least  one  important  recognized  theorem  of  physics. 
The  fact  that  he  did  not  become  conscious  of  this  contradiction, 
but  that,  on  the  contrary,  he  regarded  his  idea  as  the  most 
important  event  in  the  development  of  his  intellect,  may  be 
regarded  as  an  example  of  a  docta  ignorantia.  But  it  is 
allowable,  too,  that  philosophic  fantasies  that  complete  the 
poetical  picture  of  the  universe  should  be  given  expression. 
And  Nietzsche  would  presumably  have  been  deprived  of  a 
degree  of  pleasure  if  he  had  been  aware  of  this  second  law. 

"  Truth  is  the  most  expedient  error  "  ;  this  statement  may 
be  traced  back  to  a  sequence  of  thought  developed  by  Nietzsche. 
But  the  Eternal  Repetition  is  shattered  by  just  this  remark, 
for  judged  by  its  consequences  it  would  be  a  very  inexpedient 
error. 

Supposing  we  should  succeed  in  exchanging  thoughts  with 
the  inhabitants  of  distant  worlds  and  should,  through  them, 
acquire  the  elements  of  a  civilization  superior  to  our  own, 
would  this  knowledge  prove  a  blessing  to  us  or  the  reverse  ? 

The  word  "  superior  "  must,  of  course,  be  treated  circum- 


218  EINSTEIN  THE  SEARCHER 

spectly.  It  is  to  denote  only  that,  relatively,  this  distant 
civilization  bears  somewhat  the  same  relation  to  our  civiliza- 
tion of  to-day  as  our  own  bears  to  that  of  an  Australasian 
negro  or  an  anthropoid  ape.  There  are  fanatics  of  progress 
whose  wishes  plunge  headlong  and  without  restraint  into  the 
future,  and  to  whom  nothing  could  be  more  desirable  than  the 
sudden  appearance  of  a  civilization  that,  as  they  opine,  would 
at  one  stroke  carry  us  *'  forward  "  many  thousands  of  years. 

But  the  view  of  these  magicians  with  their  seven-league 
boots  is  untenable.  Let  me  cite  a  mere  outhne  of  the  many 
opposing  arguments  in  a  few  words  of  Einstein.  "  Every 
sudden  change  in  the  conditions  of  existence,  even  if  it  occurred 
in  the  form  of  a  higher  development,  would  come  upon  us 
like  a  doom,  and  would  probably  annihilate  us,  just  as  the 
Indians  succumb  to  the  civilization  that  has  outstripped 
them.  The  tragedy  of  our  own  highly  civilized  times  is  that 
we  cannot  create  the  social  organizations  that  have  become 
necessary  as  a  consequence  of  the  technical  advances  of  the 
last  century.  This  has  given  rise  to  the  crises,  impasses,  and 
senseless  competition  between  nations,  and  to  the  impoverish- 
ment of  defenceless  individuals.  These  deplorable  conditions 
would  become  inconceivably  accentuated  if  we  were  to  be 
invaded  by  extra-mundane  technical  sciences  of  a  higher 
order." 

Nevertheless,  there  is  still  a  possibility  that  the  "  superior 
civilization  "  might  contain  indications  of  the  organizations 
which  we  lack.  Instead  of  entering  on  the  question  of  this 
Utopia,  we  confined  ourselves  to  comparing  past  conditions 
in  our  world  with  present  ones.  Did  we  not  have  the  most 
promising  preliminaries  for  an  organization  that  was  devoid  of 
friction  and  tended  to  reduce  the  competition  between  nations 
in  the  numerous  international  institutions  that  drew  together 
a  great  section  of  the  intellectual  world  to  work  in  co-operation  ? 
Are  there  hopes  that  this  international  coalition  will  be 
resumed  ? 

Einstein  expressed  himself  optimistically,  not  to  do  homage 
to  an  organization  artificially  formed,  but  to  extol  the  world- 
wide mastery  of  intellect.  "  Even  if  international  congresses 
were  to  be  swept  away,"  he  said,  "  international  co-operation 


DISCONNECTED  SUGGESTIONS  219 

would  not  be  abolished,  as  it  effects  itself  automatically."  I 
should  venture  to  assert  that  if  all  these  congresses  were  to 
cease,  we  should  not  even  have  cause  to  fear  that  there  would 
be  an  appreciable  diminution  in  the  combined  effort  of  research. 
If  certain  developments  are  hindered  by  poUtical  conditions, 
it  is  only  due  to  the  resulting  economic  hardships  affecting 
individuals  in  their  work  and  robbing  them  of  their  intellectual 
freedom.  The  real  friends  of  Truth  have  alwa-ys  clung  to- 
gether, and  do  so  actually  now  ;  indeed,  many  feel  the  tie  to 
be  closer  than  that  connecting  them  to  their  own  country. 
In  spite  of  all  obstacles  and  boundaries  they  will  never  cease 
to  find  contact  with  one  another  ! 


CHAPTER  XI 
EINSTEIN'S  LIFE  AND  PERSONALITY 

WE  know  from  the  biographies  of  great  thinkers  that 
they  seldom  personify  the  character  of  a  dramatic 
ideal.  They  are  not  heroes  of  fiction  who  pass 
through  complex  experiences  and  struggle  with  mysterious 
problems  of  existence  that  may  unduly  excite  the  imagina- 
tion of  observers.  Whoever  follows  their  development  re- 
marks in  the  majority  of  cases  the  predominance  of  the  inner 
life,  the  course  of  which  is  discoverable  only  by  study  of  their 
works,  no  clue  being  given  in  the  confusion  of  ordinary  exterior 
manifestations.  An  eminent  man  of  thought,  whose  energies 
are  concentrated  on  mental  effort,  rarely  finds  time  to  present 
in  addition  an  interesting  figure  in  the  epic  sense.  The  poet 
who  moulds  his  forms  from  life  finds  little  scope  in  him  as  a 
model,  and  only  in  exceptional  cases  has  he  succeeded  in 
idealizing  the  savant  in  a  work  of  art. 

It  would  be  a  fruitless  undertaking  to  treat  Einstein's  life 
as  one  of  these  exceptional  cases.  It  is  possible  to  trace  the 
various  phases  of  his  development,  yet  neither  the  writer  nor 
the  reader  must  disguise  from  himself  the  fact  that  such 
outlines  give  only  the  external  picture  of  the  man  and  chrono- 
logical events  of  importance.  Nevertheless,  a  book  of  which 
he  forms  the  theme  cannot  pass  over  the  task  of  giving  his 
curriculum  vitcB.  And  if  it  should  partly  appear  aphoristic 
and  disjointed,  it  must  be  borne  in  mind  that  this  account 
originated  from  conversations  and  scraps  of  conversation 
that  touched  on  various  episodes  of  his  Hfe,  according  as  they 
had  a  bearing  on  the  subject  under  discussion. 

The  story  of  Einstein's  life  begins  at  Ulm,  the  town  which 
possesses  the  highest  building  in  Germany.  Gladly  would  I 
stand  on  the  belfry  of  the  Ulm  Cathedral  in  order  to  obtain  a 


EINSTEIN'S  LIFE  AND  PERSONALITY        221 

general  survey  of  Einstein's  youth.  But  the  view  discloses 
nothing  beyond  the  bare  fact  that  he  was  born  there  in  March 
1879.  The  detail  which  has  already  been  mentioned  above, 
namely,  that  it  was  something  physical  that  first  arrested  the 
child's  attention,  remains  to  be  noted.  His  father  once  showed 
the  infant,  as  he  lay  in  his  cot,  a  compass,  simply  with  the  idea 
of  amusing  him — and  in  the  five-year-old  boy  the  swinging 
metal  needle  awakened  for  the  first  time  the  greatest  wonder- 
ment about  unknown  cohesive  forces,  a  wonderment  that  was 
an  index  of  the  research  spirit  that  was  still  lying  dormant  in 
his  consciousness.  The  remembrance  of  this  psychical  event 
has  a  significant  meaning  for  the  Einstein  of  to-day.  In  him 
all  the  impressions  of  early  childhood  seem  to  be  still  vivid,  the 
more  so  as  all  other  physical  occurrences,  such  as  the  falling 
of  an  unsupported  body,  left  no  impression  on  him.  His 
attention  was  fixed  on  the  compass,  and  the  compass  alone. 
This  instrument  addressed  him  in  oracular  language,  indicating 
to  him  an  electromagnetic  field  that  was  in  later  years  to 
serve  him  as  a  domain  for  fruitful  research. 

His  father,  who  had  a  sunny,  optimistic  temperament,  and 
was  inclined  towards  a  somewhat  aimless  existence,  at  this 
time  moved  the  seat  of  the  family  from  Ulm  to  Munich.  They 
here  Hved  in  a  modest  house  in  an  idyllic  situation  and  sur- 
rounded by  a  garden.  The  pure  joy  of  Nature  entered  into 
the  heart  of  the  boy,  a  feeling  that  is  usually  foreign  to  the 
youthful  inhabitants  of  cities  of  dead  stone.  Nature  whis- 
pered song  to  him,  and  at  the  coming  of  the  spring-tide  infused 
his  being  with  joy,  to  which  he  resigned  himself  in  happy 
contemplation.  A  religious  imdercurrent  of  feeling  made 
itself  manifest  in  him,  and  it  was  strengthened  by  the  ele- 
mentary stimulus  of  the  scented  air,  of  buds  and  bushes,  to 
which  was  added  the  educational  influence  of  home  and 
school.  This  was  not  because  ritualistic  habits  reigned  in  the 
family.  But  it  had  so  happened  that  he  learned  simultaneously 
the  teachings  of  the  Jewish  as  well  as  the  Catholic  Church  ; 
and  he  had  extracted  from  them  that  which  was  common 
and  conducive  to  a  strengthening  of  faith,  and  not  what 
conflicted. 

Youthful  impetuosity,  which  in  boys  of  a  similar  age 
usually  expresses  itself  in  rash  enterprises  and  loose  tricks,  did 


222  EINSTEIN  THE  SEARCHER 

not  appear  in  him.  His  spirit  was  adjusted  to  contemplation, 
and  an  inborn  fatalism,  diffused  with  a  super-sensuous  element 
appertaining  to  dreams,  restrained  him  from  responding  to 
external  impulses.  He  reacted  slowly  and  hesitatingly,  and 
he  interpreted  what  his  senses  offered  him  and  all  the  Httle 
experiences  of  early  days  in  terms  of  a  reverence  reflected  from 
within.  Words  did  not  easily  rise  from  his  lips,  and  measured 
by  the  ordinary  scale  of  rapidity  of  learning  and  readiness  in 
answering  questions,  he  would  scarcely  have  been  judged  to 
possess  unusual  gifts.  As  an  infant  he  had  started  to  talk 
so  late  that  his  parents  had  been  in  some  alarm  about  the 
possibility  of  an  abnormality  in  their  child.  At  the  age  of 
eight  or  nine  years  he  presented  the  picture  of  a  shy,  hesitating, 
unsociable  boy,  who  passed  on  his  way  alone,  dreaming  to 
himself,  and  going  to  and  from  school  without  feeling  the  need 
of  a  comrade.  He  was  nicknamed  "  Biedermaier,"  because  he 
was  looked  on  as  having  a  pathological  love  for  truth  and 
justice.  What  at  that  time  seemed  to  be  pathological,  to-day 
appears  as  a  deeply  rooted  and  irrepressible  natural  instinct. 
Whoever  has  got  to  know  Einstein  as  a  man  and  as  a  scientist 
knows  that  this  failing  of  his  boyhood  was  but  the  forerunner 
of  a  very  healthy  outlook. 

Signs  of  his  love  for  music  showed  themselves  very  early. 
He  thought  out  little  songs  in  praise  of  God,  and  used  to  sing 
them  to  himself  in  the  pious  seclusion  that  he  preserved  even 
with  respect  to  his  parents.  Music,  Nature,  and  God  became 
intermingled  in  him  in  a  complex  of  feeling,  a  moral  unity, 
the  traces  of  which  never  vanished,  although  later  the  religious 
factor  became  extended  to  a  general  ethical  outlook  on  the 
world.  At  first  he  clung  to  a  faith  free  from  all  doubt,  as  had 
been  infused  into  him  by  the  private  Jewish  instruction  at 
home  and  the  Catholic  instruction  at  school.  He  read  his 
Bible  without  feeUng  the  need  of  examining  it  critically  ;  he 
accepted  it  as  a  simple  moral  teaching  and  found  himself  little 
inclined  to  confirm  it  by  rational  arguments  inasmuch  as  his 
reading  extended  very  little  beyond  its  circle. 

Painful  inner  conflicts  were  not  wanting.  Jewish  children 
formed  a  small  minority  in  the  school,  and  it  was  here  that  the 
boy  Albert  felt  the  first  ripples  of  the  anti-semitic  wave  that, 
sweeping  on  from  without,  was  threatening  to  overwhelm 


EINSTEIN'S  LIFE  AND  PERSONALITY        223 

master  and  pupil  alike.  For  the  first  time  he  felt  himself 
oppressed  by  something  that  was  not  in  harmony  with  his  simple 
temperament.  His  modesty  made  him  a  prey  to  injustice, 
and  in  defending  himself  his  originally  gentle  and  restrained 
nature  gained  a  certain  independence  and  individuahty. 

If  one  may  speak  of  achievements  at  all  in  a  preparatory 
school,  those  of  Albert  were  of  the  average  modest  level.  He 
was  careful  as  a  pupil,  generally  satisfied  requirements,  but  in 
no  way  betrayed  special  talents  :  indeed,  so  much  the  less,  as 
he  showed  himself  to  be  possessed  of  a  very  uncertain  memory 
for  words.  The  methodic  plan  of  the  elementary  school  that 
he  attended  to  his  tenth  year  was,  however,  not  other  than 
the  usual  scheme  mapped  out  by  drill-masters  ;  it  made  up 
for  what  was  lacking  in  an  understanding  of  the  pupils  by 
applying  drastic  strictness.  The  beautiful  sentence  of  Jean 
Paul :  "  Memory  is  the  only  paradise  from  which  we  cannot 
be  banished,"  finds  no  echo  in  Einstein's  school  memories, 
of  which  he  has  often  spoken  to  me  without  a  shadow  of  regret 
for  a  lost  paradise.  He  told  me  with  bitter  sarcasm  that  his 
teachers  had  the  character  of  sergeants — ^those  later  in  the 
gymnasium  (secondary  school)  were  of  the  nature  of  lieutenants. 
Both  terms  are  used  in  the  pre-armistice  sense,  and  his  words 
were  directed  against  the  self-opinionated  tone  and  customs 
of  these  garrison-schools  of  earher  days. 

The  next  stage  of  his  development  was  a  course  of  study 
at  the  Luitpold-Gymnasium  in  Munich,  which  placed  him  in 
the  second  class.  In  Einstein's  retrospect  of  these  days  more 
friendly  recollections  present  themselves,  connected,  however, 
only  with  particular  persons,  and  not  breathing  praise  in 
general ;  on  the  contrary,  from  his  account,  it  is  clear  that 
although  he  conceived  affection  for  individual  teachers,  he 
felt  the  tone  of  the  institute  as  a  whole  to  be  rough.  As  we 
know,  many  things  have  been  changed  in  these  schools  since 
then,  following  on  a  revulsion  from  the  convict  atmosphere 
that  used  to  characterize  them,  and  which  meant  suffering 
enough  for  the  pupils.  The  result  was  that  the  schoolboy 
Einstein  developed  a  contempt  for  human  institutions  and 
assigned  Uttle  value  to  the  subjects  of  study  which  he  was 
obhged  to  absorb  in  schematic  form  without  the  application  of 
his  own  mentad  energy.    This  gloomy  picture  is  relieved  at 


224  EINSTEIN  THE  SEARCHER 

points  by  the  presence  of  several  teachers,  above  all,  one  called 
Ruess,  who  took  pains  in  exposing  the  beauty  of  classical 
antiquity  to  the  fourteen-year-old  boy.  We  learn  elsewhere 
that  Einstein  at  present  admits  the  humanistic  ideal  for  the 
school  of  the  future  only  under  very  restricted  limitations. 
But  when  he  thinks  of  this  teacher  and  his  influence,  a  warm 
appreciation  of  classical  study  vibrates  in  his  words,  occasion- 
ally rising,  indeed,  to  an  unbounded  enthusiasm  for  the  treasures 
of  Greek  history  and  literature.  His  instruction  was  not 
restricted  to  the  acquisition  of  a  perspective  of  the  antique. 
Under  the  direction  of  the  same  teacher,  he  was  introduced 
into  the  poetic  world  of  his  native  country,  and  learned  the 
magic  of  Goethe  in  his  "  Hermann  and  Dorothea  *'  ;  this  poem, 
as  he  confesses,  was  explained  to  him  in  a  really  model  manner. 
Thus  there  were  some  oases  in  the  desert  of  schematic  teaching  : 
they  served  as  refreshing  halts  for  the  spirit  of  the  eager  young 
searcher  after  knowledge. 

We  must  go  back  one  or  two  years  to  note  a  weighty  ex- 
perience, which  occurred  when  he  made  his  first  acquaintance 
with  elementary  mathematics  ;  this  subject  presented  itself 
to  him  with  the  intensity  of  a  revelation.  It  did  not  happen  in 
the  ordinary  course  of  school- work,  but  was  due  to  a  sort  of 
wizard-like  inquiring  inner  spirit  that  plied  him  with  questions 
and  that  gave  him  inward  thrills  of  joy  when  he  found  a  sharp- 
witted  solution.  From  the  very  beginning  Albert  proved 
himself  to  be  a  good  solver  of  problems,  even  before  he  achieved 
an  arithmetical  virtuosity,  and  before  he  knew  the  technique 
of  equations.  He  helped  himself  by  means  of  little  tricks, 
experimented  roundabout  inventions,  and  was  happily  excited 
when  they  led  to  the  goal.  One  day  he  asked  his  uncle,  Jacob 
Einstein,  an  engineer  who  lived  in  Munich,  a  certain  question.  He 
had  heard  the  word  "  algebra  "  andsurmisedthat  his  uncle  would 
be  able  to  explain  the  term  to  him.  Uncle  Jacob  answered  : 
'*  Algebra  is  the  calculus  of  indolence.  If  you  do  not  know  a 
certain  quantity,  you  call  it  x  and  treat  it  as  if  you  do  know  it, 
then  you  put  down  the  relationship  given,  and  determine  this 
X  later."  That  was  quite  sufficient.  The  boy  received  a  book 
containing  algebraic  problems  that  he  solved  all  alone  in  accord- 
ance with  this  not  exhaustive  but  expedient  direction.  On 
another  occasion  Uncle  Jacob  told  him  the  enunciation  of 


EINSTEIN'S  LIFE  AND  PERSONALITY        225 

Pythagoras'  theorem  without  giving  him  a  proof.  His  nephew 
understood  the  relationship  involved,  and  felt  that  it  had  to 
be  founded  on  some  reasoning.  Again  he  set  about  all  alone 
to  furnish  what  was  wanting.  This  was,  however,  not  a  case  for 
the  "  calculus  of  indolence  "  with  an  x  that  was  to  be  deter- 
mined. Here  it  was  a  question  of  developing  a  facility  for 
geometric  argument,  such  as  very  few  possess  at  such  an  early 
stage  of  development.  The  boy  plunged  himself  for  three 
weeks  into  the  task  of  solving  the  theorem,  using  all  his  power 
of  thought.  He  came  to  consider  similarity  of  triangles  (by 
dropping  a  perpendicular  from  one  vertex  of  the  right-angled 
triangle  on  to  the  hypotenuse),  and  was  thus  led  to  a  proof 
for  which  he  had  so  ardently  longed  !  And  although  it  con- 
cerned only  a  very  old  well-known  theorem,  he  experienced 
the  first  joy  of  the  discoverer.  The  proof  that  he  had  found 
proved  that  the  ingenuity  of  the  worrying  young  mind  was 
awakening. 

A  new  world  was  opened  for  him  when  he  made  the  acquaint- 
ance of  A.  Bernstein's  comprehensive  popular  books  on  scientific 
subjects.  This  work  is  looked  on  nowadays  as  being  some- 
what antiquated  and,  in  the  eyes  of  many  a  professional 
scientist,  has  sunk  to  the  level  of  a  pseudo-scientific  "  shocker  " ; 
even  when  Einstein  as  a  boy  made  explorations  in  it,  there  were 
signs  of  rust  and  decay  in  the  work,  for  it  originated  in  the 
fifties  of  the  previous  century  and,  in  point  of  subject-matter, 
had  long  been  transcended.  Yet  it  could  be  read  then — and 
even  now — as  a  story  containing  thousands  of  interspersed 
phj^ical,  astronomical,  and  chemical  wonders,  and  for  the  boy 
Einstein  it  came  to  be  a  true  book  of  Nature,  which  presented 
to  his  mind,  greedy  for  knowledge,  as  much  as  it  did  to  his 
imagination. 

Other  vistas  were  opened  up  to  him  by  Biichner's  Kraft 
und  Stoff  [Force  and  Substance),  a  book  the  cheapness  of  which 
he  could  not  yet  discern,  but  which  called  up  wonder  in  him 
without  rousing  his  criticism.  In  addition,  his  attention  was 
chiefly  occupied  by  a  handbook  of  elementary  planimetry, 
containing  an  abundance  of  geometrical  exercises,  which  he 
fearlessly  attacked  and  within  a  very  short  time  solved  almost 
in  their  entirety.  His  delight  grew  when  he  ventured  into 
the  difficulties  of  analytical  geometry  and  infinitesimal  calculus 
15 


226  EINSTEIN  THE  SEARCHER 

quite  apart  from  the  curriculum  of  his  school-work.  Lubsen*s 
textbook  had  fallen  into  his  hands,  and  these  directions 
sufficed  for  his  audacious  spirit.  Whereas  many  of  his  school 
companions  were  still  standing  undecidedly  before  the  pools 
of  theorems  of  congruence  and  repeating  decimals,  he  was 
already  disporting  himself  freely  in  the  ocean  of  infinitesimals. 
His  work  did  not  remain  concealed,  and  gained  appreciation. 
His  mathematical  teacher  declared  that  the  fifteen-year-old 
boy  was  ripe  for  university  study. 

Yet  he  was  not  to  find  a  way  into  the  open  by  matriculating 
very  early,  but  through  an  event  that  unexpectedly  threw 
him  into  new  surroundings  of  life.  In  1894  his  parents  trans- 
ferred their  abode  to  Italy.  The  chronicler  has  nothing  to 
report  of  pangs  of  separation  in  Albert  when  he  left  Bavarian 
soil.  He  was  glad  to  get  away  from  the  drill  academy,  Luitpold, 
and,  as  an  inhabitant  of  Milan,  he  enjoyed  the  change  in  his 
existence,  and  was  not  encumbered  by  attacks  of  home-sick- 
ness. All  in  all,  he  had  felt  himself  in  an  unhappy  position 
under  school  compulsion  in  Munich,  in  spite  of  the  mathe- 
matical delights  he  had  provided  for  himself,  and  in  spite  of  the 
rapturous  moments  that  musical  revelations  had  created  for 
him  since  his  twelfth  year.  Defiance  and  distrust  against  out- 
side influences  had  remained  active  in  him  as  forces  that  did  not 
allow  the  happy  disposition  proper  to  his  age  to  assert  itself. 
But  now  the  fetters  had  fallen  and  the  pent-up  joy  of  fife 
burst  forth  as  if  through  opened  sluices.  The  sun  and  land- 
scape of  the  South,  Italian  manners  of  life,  art  freely  displayed 
in  the  matket -place  and  on  the  street,  realized  for  him  dream- 
pictures  that  had  appeared  to  him  earlier  during  the  hours 
of  oppression.  Whatever  he  saw,  felt,  and  experienced  lay 
outside  the  ordinary  course  of  his  life,  awakened  his  sense  for 
natural  and  human  things,  and  set  his  spirit  free  from  all  bonds. 
There  was  no  question  of  his  going  to  school  in  the  first  six 
months.  He  enjoyed  complete  freedom,  occupied  himself 
with  literature,  and  undertook  extended  excursions.  Starting 
from  Pa  via,  he  wandered  all  alone  over  the  Apennine  to  Genoa. 
Whilst  he  was  being  intoxicated  with  the  sublime  Alpine 
landscape,  he  came  into  contact  with  the  lower  stratum  of 
the  people,  who  aroused  his  deepest  sympathy.  The  tour 
took  him  over  a  short  stretch  of  the  Italian  Riviera,  the 


EINSTEIN'S  LIFE  AND  PERSONALITY        227 

beauties  of  which,  as  depicted  by  Bocklin,  do  not  seem  to 
have  revealed  themselves  to  him.  At  that  time  he  was 
probably  subject  to  a  feehng  of  upward  striving  such  as 
possessed  Zarathustra. 

With  all  their  joys  and  inspirations  the  experiences  in  Italy 
remained  but  a  short  episode.  Einstein  resolved  on  a  new 
tour,  which  was  not  without  a  professional  purpose.  He  made 
a  pilgrimage  to  Switzerland  with  the  intention  of  studying 
mathematics  and  physics  at  the  Ziirich  Polytechnical  Institute. 
But  he  was  not  to  be  successful  in  his  first  effort  to  gain  entrance. 
The  conditions  of  entry  required  a  standard  in  descriptive 
sciences  and  modern  languages  that  he  had  not  yet  reached. 
So  he  turned  to  Aarau,  where  he  was  allowed  to  extend  his 
knowledge  with  the  help  of  excellent  methods  at  the  Canton 
school.  Even  at  the  present  day  Einstein  talks  with  extreme 
enthusiasm  of  the  organization  of  this  model  school  that  corre- 
sponds in  rank  approximately  to  a  German  Realgymnasium 
(or  an  EngUsh  Grammar  School).  There  was  nothing  to 
remind  him  of  the  continual  manipulation  of  the  sceptre  of 
authority  at  the  Luitpold  school  barracks  ;  he  easily  obtained 
his  leaving  certificate,  and  now  the  portals  of  the  Ziirich 
Polytechnicum  were  open  for  him. 

He  himself  was  probably  not  aware  that  he  carried  a 
marshal's  baton  in  his  own  mathematical  equipment.  But, 
in  looking  back,  we  come  across  astounding  things.  For  it 
is  a  fact  that  even  in  the  pupil  at  Aarau  problems  had  taken 
root  that  already  lay  in  the  vanguard  of  research  at  that 
time.  He  was  not  yet  a  finder,  but  what  he  sought  as  a 
sixteen-year-old  boy  was  already  stretching  into  the  realms 
of  his  later  discoveries.  We  have  here  simply  to  register 
facts,  and  to  abstain  from  making  an  anal5^is  of  his  develop- 
ment, for  how  are  we  to  trace  out  the  intermediate  steps,  and 
to  discover  the  sudden  phases  of  thought  that  lead  a  very 
young  Canton  pupil  to  feel  his  way  into  a  still  undiscovered 
branch  of  physics  ?  The  problem  that  occupied  him  was 
the  optics  of  moving  bodies,  or,  more  exactly,  the  emission 
of  Hght  from  bodies  that  move  relatively  to  the  ether.  This 
contains  the  first  flash  of  the  grandiose  complex  of  ideas  that 
was  later  to  lead  to  a  revision  of  our  picture  of  the  world. 
And  if  a  biographer  should  state  that  the  first  'jeginnings  of 


228  EINSTEIN  THE  SEARCHER 

the  doctrine  of  relativity  occurred  at  that  time,  he  would  not 
be  making  an  objectively  false  statement. 

The  ambitions  of  the  youth  by  no  means  reached  these 
flights  of  imagination,  for  whereas  the  latter  signified  the  coming 
power  of  his  wings,  he  himself  set  a  modest  goal.  He  wished 
to  become  a  schoolmaster,  and  imagined  that  in  choosing  this 
career  he  was  allowing  his  hopes  to  run  high.  This  was  in 
conformity  with  the  esteem  in  which  he  held  the  status  of 
teachers.  In  the  Zurich  Technical  School  there  is  a  section 
equipped  as  a  department  for  preparing  teachers,  and  in  this 
Einstein  studied  from  the  age  of  seventeen  to  the  age  of 
twenty-one,  perfectly  satisfied  with  the  thought  of  sitting,  not 
on  the  pupil's  bench,  but  at  the  master's  desk,  and  of  exercising 
a  beneficial  if  limited  influence  as  a  preceptor  of  the  young. 

He  was  still  under  the  sway  of  the  feeling  that  he  was 
not    sufficiently  experienced   in    life    and   that  he  dare  not 
venture  out  into  the  fight  for  existence  in  the  great  turmoil 
of  the  world.     He  saw  in  this  struggle,  which  pitted  man 
against   man,   led  to  exhibitions   of    violence,   and  aroused 
ambition   for   glittering   unreaHties,  cause   only  for   disgust 
and  alienation.     The  prospect  of    personal  success  did  not 
lure  him  to  try  force  against  force.     Thus,  for  the  time  being, 
it  was  his  ideal  to  lead  a  very  modest  existence.     From  various 
quarters  he  had  been  given  hopes  of  a  position  as  assistant  to 
some  professor  of  physics  or  mathematics.     But  for  unknown 
reasons  he  was  everywhere  refused.     These  apparently  obscure 
grounds,  it  must  be  said  with  regret,  become  clearer  when  we 
bear  in  mind  his  confession  of  faith.     Nor  did  his  hopes  of 
teaching  at  a  gymnasium  seem  near  fulfilment,  as  certain 
conditions  of  birth  raised  obstacles.     In  the  first  place,  he  was 
not  a  Swiss  ;  in  fact,  since  his  stay  in  Milan  he  was  without  a 
nationality  at  all  in  the  bureaucratic  sense,  and  then  he  had 
no  personal  connexions,  without  which,  at  least  at  that  time, 
there  was  no  chance  of  progress  even  for  a  talented  person. 
Yet  the  young  student  who  was  entirely  without  protection 
of  any  sort  had  to  overcome  the  cares  and  satisfy  the  needs  of 
daily  Ufe.     He  could  not  rely  on  material  help  from  his  parents, 
who  themselves  lived  in  restricted  circumstances,  and  thus 
we  find  him  a  little  later  in  Schaffhausen  and  Bern,  where  he 
earned  a  small  pittance  as  a  private  tutor. 


EINSTEIN'S  LIFE  AND  PERSONALITY        229 

He  found  consolation  in  the  fact  that  he  preserved  a 
certain  independence,  which  meant  the  more  to  him  as  his 
instinct  for  freedom  led  him  to  discover  the  essential  things 
in  himself.  Thus,  earlier,  too,  during  his  studies  at  Ziirich 
he  had  carried  on  his  work  in  theoretical  physics  at  home, 
almost  entirely  apart  from  the  lectures  at  the  Polytechnic, 
plunging  himself  into  the  writings  of  Kirchhoff,  Helmholtz, 
Hertz,  Boltzmann,  and  Drude.  Disregarding  chronological 
order,  we  must  here  mention  that  he  found  a  partner  in  these 
studies  who  was  working  in  a  similar  direction,  a  Southern 
Slavonic  student,  whom  he  married  in  the  year  1903.  This 
union  was  dissolved  after  a  number  of  years.  Later  he  found 
the  ideal  of  domestic  happiness  at  the  side  of  a  woman  w^hose 
grace  is  matched  by  her  intelligence.  Else  Einstein,  his  cousin, 
whom  he  married  in  Berlin. 

In  1 90 1,  after  living  in  Switzerland  for  five  years,  he 
acquired  the  citizenship  of  Ziirich,  and  this  at  last  gave  him 
the  opportunity  of  rising  above  material  cares.  His  Uni- 
versity friend.  Marcel  Grossmann,  lent  him  a  helping  hand  by 
recommending  him  to  the  Swiss  Patent  Office,  the  director  of 
which  was  his  personal  friend.  Einstein  occupied  himseK  here 
from  1902  to  1905  as  a  technical  expert,  that  is,  as  an  examiner 
of  appHcations  for  patents,  and  this  position  gave  him  the 
chance  of  moving  about  in  absolute  freedom  in  the  realms  of 
technical  science.  Whoever  has  a  strong  predilection  for 
discovery  will  perhaps  feel  estranged  to  find  Einstein  so  long 
in  the  sphere  of  "  invention,"  but,  as  Einstein  himself  em- 
phasizes very  strongly,  both  regions  make  great  demands  on 
clearly  defined  and  accurate  thought.  •  He  recognizes  a  definite 
relationship  between  the  knowledge  that  he  gained  at  the 
Patent  Office  and  the  theoretical  results  that  appeared  at  the 
same  time  as  products  of  intensive  thought. 

In  1905,  in  the  midst  of  his  work,  the  storm  broke  loose  in 
him  with  the  suddenness  of  a  hurricane.  In  quick  succession 
his  mind  disburdened  itself  of  the  abundance  of  ideas  that 
had  stored  themselves  up  in  the  work  of  the  preceding  years, 
and  these  ideas  signify  more  to  us  than  a  definite  stage  in  the 
development  of  an  individual.  What  physicists  have  come 
to  regard  as  an  elaboration  of  the  heritage  of  Galilei  and 
Newton  had  matured  in  him.    We  merely  record  the  title 


230  EINSTEIN  THE  SEARCHER 

of  dissertations,  which  appeared  in  1905  in  the  Annalen  der 
Physik  :  "  Concerning  a  Heuristic  Standpoint  towards  the  Pro- 
duction and  Transformation  of  Light  " — "  Concerning  the 
Inertia  of  Energy  " — "  The  Law  of  Brownian  Movement." 
— Then  the  most  important  contribution  :  ''  The  Electro- 
dynamics of  Moving  Bodies,"  that  contained  the  revolutionary 
ideas  underlying  the  special  theory  of  relativity.  To  these  is  to 
be  added  a  dissertation  for  his  doctorate  in  the  same  year  : 
"  A  New  Determination  of  Molecular  Dimensions." 

In  all,  these  represent  a  Ufe-work  that  belongs  to  the 
history  of  science.  It  was  certainly  some  considerable  time 
before  his  work  began  its  triumphal  march  in  the  sight  of  the 
world,  and  it  may  be  added  that  treasures  were  hidden  in  these 
disquisitions  that  were  not  understood  till  long  years  after- 
wards. Yet  the  youthful  discoverer  was  not  passed  over 
without  signs  of  friendly  appreciation.  He  received  a  letter, 
couched  in  very  warm  terms,  from  the  celebrated  physicist, 
Max  Planck,  who  was  a  complete  stranger  to  him  at  that 
time  ;  it  spoke  in  glowing  words  of  his  essay,  "  The  Electro- 
dynamics of  Moving  Bodies."  This  letter  was  the  first 
diploma,  the  forerunner  of  all  the  honours  that  later  swept  over 
him  like  a  tidal  wave. 

It  was  his  intention  to  obtain  a  tutorial  position  at  the  Uni- 
versity. An  appointment  to  Bern  was  at  first  again  hindered 
by  certain  obstacles  which  he  would  probably  have  overcome 
if  he  had  applied  himself  energetically  to  attaining  his  goal. 
He  finally  received  his  appointment,  but  exercised  his  duties 
for  only  a  very  short  time,  as  Ziirich  now  opened  her  arms  to 
him.  In  1909  he  accepted  the  position  of  Professor  extra- 
ordinarius  there  for  theoretical  physics,  and  soon  assembled 
a  grateful  audience  about  himself.  Nevertheless,  during  the 
earlier  stages  of  his  professorship  he  found  it  difficult  to  sup- 
press a  longing  for  the  quiet,  unexcited  life  of  his  patent -office 
work,  in  which  he  seemed  to  have  had  a  still  greater  degree 
of  independence.  In  191 1  he  accepted  a  new  appointment 
as  Professor  ordinarius  to  Prague,  which  offered  him  more 
favourable  emoluments  as  an  inducement.  In  the  autumn  of 
1912  he  returned  to  Zurich  as  a  Professor  at  the  Polytechnic, 
and  in  the  early  part  of  1914  he  was  drawn  into  the  strong 
magnetic  field  of  the  northern  capital ;  he  arrived  at  the  Spree, 


EINSTEIN'S  LIFE  AND  PERSONALITY        231 

and  has,  since  then,  lived  among  us.  He  is  now  a  Swiss  by 
nationality,  a  world  citizen  by  conviction,  and,  professionally, 
a  member  of  the  Berlin  Academy  and  attached  in  a  lecturing 
capacity  to  the  University.  Here  he  perfected  his  works  on 
relativity,  ending  in  the  superlative  elaboration  of  the  theory 
of  gravitation,  the  beginnings  of  which  stretch  back  to  the 
year  1907.  He  had  spent  eight  years  in  a  concentrated  effort 
of  severe  thought  to  bring  it  to  completion,  and  perhaps 
centuries  will  be  necessary  before  the  world  will  gain  a  com- 
plete perspective  of  all  the  consequences  of  his  theory. 

For  the  theory  asks  us  to  brush  aside  habits  of  thought 
that  have  claimed  an  hereditary  position  in  pre-eminent  minds. 
One  of  the  foremost  physicists,  Henri  Poincare,  had  confessed 
as  late  as'1910  that  it  caused  him  the  greatest  effort  to  find 
his  way  into  Einstein's  new  mechanics.  Another  whole  year 
passed  before  he  gave  up  his  last  doubts.  Then  he  passed 
with  flying  colours  into  Einstein's  camp,  and  recommended 
Einstein's  appointment  to  the  Professorship  at  Ziirich,  in  con- 
junction with  the  discoverer  of  radium,  Madame  Curie,  in  an 
exuberant  letter  which  may  add  its  note  of  appreciation  here  : 

"  Herr  Einstein,"  so  wrote  the  great  Poincare,  "  is  one  of 
the  most  original  minds  that  I  have  ever  met.  In  spite  of  his 
youth  he  already  occupies  a  very  honourable  position  among 
the  foremost  savants  of  his  time.  What  we  marvel  at  in  him, 
above  all,  is  the  ease  with  which  he  adjusts  himself  to  new 
conceptions  and  draws  all  possible  deductions  from  them.  He 
does  not  cling  tightly  to  classical  principles,  but  sees  all  con- 
ceivable possibilities  when  he  is  confronted  with  a  physical 
problem.  In  his  mind  this  becomes  transformed  into  an 
anticipation  of  new  phenomena  that  may  some  day  be  verified 
in  actual  experience.  .  .  .  The  future  will  give  more  and  more 
proofs  of  the  merits  of  Herr  Einstein,  and  the  University  that 
succeeds  in  attaching  him  to  itself  may  be  certain  that  it  will 
derive  honour  from  its  connexion  with  the  young  master." 

We  may  be  tempted  to  look  back  and  ask  whether  the 
criteria  that  Wilhelm  Ostwald  once  set  up  as  a  test  of  great 
men  are  verified  in  Einstein's  case.  He  has  certainly  not 
broken  the  first  and  most  general  rule,  the  principle  of  "  early 
maturity."  This  showed  itself  clearly  when  his  impulse  to- 
wards mathematical  knowledge  and  discovery  asserted  itself. 


232  EINSTEIN  THE  SEARCHER 

and  when  he  penetrated  far  into  the  future  with  his  optical 
problems.  The  history  of  science  and  of  art  may  offer  more 
striking  examples  in  this  connexion,  but  at  any  rate  in 
Einstein's  case  the  indications  are  sufficient  to  serve  as  a  con- 
firmation of  the  rule.  On  the  other  hand,  the  second  test  of 
Ostwald  seems  to  be  valid  only  conditionally  when  applied  to 
Einstein.  For  Ostwald  takes  up  arms  against  a  "  gradual 
intensification  "  of  ability,  and  proclaims  it  as  an  almost 
universal  rule  that  the  exceptional  achievement  is  the  privilege 
of  quite  young  persons  :  "  what  he  achieves  later  is  seldom 
as  impressive  as  his  first  brilHant  achievement."  Thus,  in 
Einstein's  case,  the  exception  is  evident.  For  if  we  fix  on 
only  two  chief  discoveries,  passing  over  many  others,  there  is 
no  doubt  that  the  second  (the  theory  of  gravitation)  surpasses 
the  first  (special  relativity)  in  both  range  and  significance. 
Indeed,  we  cannot  escape  from  the  idea  of  a  "  gradual  in- 
tensification," for  the  second  discovery  could  come  about  only 
as  a  result  of  the  first.  Moreover,  it  is  not  yet  night,  and  there 
is  nothing  to  refute  the  assumption  that  there  will  be  a  further 
progression. 

Furthermore,  Ostwald  takes  into  consideration  the  tempo 
of  the  intellectual  pulse  of  inspiration  to  divide  the  main 
types  of  great  men  into  a  classical  and  a  romantic  category  : 
this  classification  cannot,  however,  be  appHed  to  Einstein. 
He  is  decidedly  classical,  in  so  far  as  his  work  seems  calculated 
to  serve  later  generations  as  a  classical  foundation  for  all 
mechanical  investigations  of  the  macrocosm  of  the  heavens 
and  the  microcosm  of  atoms.  On  the  other  hand,  his  ver- 
satility, the  mobility  and  resource  of  his  highly  imaginative 
mind,  stamp  him  as  a  romantic  spirit.  His  deUght  in  teaching 
would  also  assign  him  to  this  category,  for  in  the  case  of  many 
classical  spirits  there  is  a  decided  aversion  to  imparting  in- 
struction. So  that,  although  we  might  well  be  able  to  speak 
of  a  synthesis  of  these  two  forms,  it  seems  better  to  estimate 
Einstein,  not  in  the  light  of  a  ready  scheme,  but  rather  as  a 
type  of  which  he  is  the  unique  representative. 

Just  as  the  external  contour  of  his  life  is  on  the  whole 
regular  and  unbroken,  so  also  his  inner  life  is  attuned  to 
simplicity.     Nowhere,  it  might  almost  be  said,  do  we  observe  a 


EINSTEIN'S  LIFE  AND  PERSONALITY        283 

break,  a  spasmodic  turn,  or  a  sudden  intensification.  Although 
he  has  grasped  and  suggested  so  many  problems,  he  himself 
presents  no  psychological  riddle,  and  we  meet  with  no 
singularities  in  analysing  his  personality.  It  has  already 
been  remarked  several  times  that  Art  plaj^  a  part  in  his  life. 
What  I  learned  from  him  himself  about  his  affection  for  music 
coincides  exactly  with  what  observation  clearly  discloses. 
The  expression  of  his  countenance  when  he  is  listening  to 
music  is  a  suf&cient  indication  of  the  resonances  induced  in 
him.  He  is  confessedly  a  classicist,  and  a  sincere  devotee  of 
the  revelations  of  Bach,  Haydn,  and  Mozart.  What  fascinates 
and  enraptures  him  above  all  is  that  which  is  directed  inwards, 
which  is  contemplative  and  erected  on  a  reUgious  basis.  The 
simple  masterful  flow  in  musical  development  and  invention 
is  all-important  for  him.  The  architectonic  structure  that  we 
marvel  at  in  Bach,  the  Gothic  tendency  towards  heavenly 
heights,  perhaps  calls  up  in  him  sensations  that  emanate  from 
his  hidden  wealth  of  constructive  mathematical  ideas.  It 
seems  to  me  that  this  possibiHty  is  not  unworthy  of  remark. 
It  suggests  a  reason  for  the  fact  that  he  gives  himself  up  only 
unwillingly  to  the  nervous  strain  of  drama  directed  at  emo- 
tional upheaval.  He  does  not  gladly  overstep  the  boundary 
that  separates  the  simple  from  the  psychologically  subtle,  and 
whenever  his  desire  to  understand  art  requires  him  to  venture 
beyond  it,  his  appreciation  is  not  accompanied  by  genuine 
pleasure.  His  subjectivity  does  not  fix  this  boundary  in 
accordance  with  the  ordinary  rules  of  concert  aesthetics,  which 
are  actuall}^  not  rules  at  all,  but  only  changeable  valuations 
and  crystallizations  of  the  feelings  of  certain  groups  of  people. 
He  gives  himself  up  quietly  and  freely  to  what  is  presented, 
but  makes  no  special  effort  to  assimilate  experiences  to  which 
his  being  does  not  spontaneously  react.  There  would  be  no 
meaning  in  seeking  to  mark  off  the  Hmits  of  his  receptivity  in 
accordance  with  this,  and  to  tell  him  that  it  is  too  limited,  and 
that  it  should  be  enlarged,  and  that  he  should  not  regard  as  an 
opinionated  exaggeration  what  appears  to  others  to  be  a  deep 
and  mighty  revelation,  or  seems  to  be  possessed  of  divine 
sweetness.  He  would  be  able  to  point  out  that  even  in  the 
case  of  masters  of  the  musical  art  a  change  of  faith  was  not 
a  rare  occurrence,  and  that  they  learned  anew,  or  rejected  what 


234  EINSTEIN  THE  SEARCHER 

they  once  idolized,  and  very  often  found  no  permanent  haven 
in  their  own  faith.  Whoever,  Uke  Einstein,  gives  himself  up 
to  the  simply  contemplative,  and  feels  no  impulse  towards 
sensationalism,  is  spared  the  task  of  learning  afresh,  and  finds 
still  one  world  left  for  him  even  if  many  other  worlds  are  in- 
accessible. To  mention  only  the  main  features,  then,  neither 
Beethoven  as  a  composer  of  symphonies,  nor  Richard  Wagner, 
denote  the  pinnacles  of  music  for  him  ;  he  could  live  without 
the  Ninth  Symphony,  but  not  without  Beethoven's  ensemble 
music.  The  number  of  composers  and  compositions  which 
are  not  a  necessity  of  Ufe  for  him  is  very  considerable.  It 
includes  the  majority  of  romanticists,  the  erotically  inclined 
school  of  Chopin  and  Schumann,  which  revels  in  sensation, 
and,  as  already  mentioned,  the  neo-German  dramatic  com- 
posers. He  has  much  objective  admiration  for  them,  yet  he 
does  not  conceal  the  fact  that  he  also  feels  lively  opposition 
in  the  gamut  of  his  sensations.  He  regards  the  properly 
modern  productions  as  interesting  phenomena,  and  has 
various  degrees  of  disapproval  for  them,  extending  to  complete 
aversion.  It  costs  him  an  effort  to  hear  an  opera  of  Wagner, 
and  when  he  has  done  so,  he  returns  home  bearing  with  him 
the  leitmotiv  of  Meister  Eckhard  :  **  The  lust  of  creatures  is 
intermingled  with  bitterness."  In  general  he  seems  to  take 
up  approximately  the  point  of  view  of  Rossini.  Wagner 
gives  him  wonderful  moments,  followed,  however,  by  periods 
of  acute  emotional  distress.  I  need  hardly  add  that  I  myself, 
who  confess  to  being  an  ultra-Wagnerite,  never  strove  in  my 
conversations  with  Einstein  to  make  my  opinion  prevail 
against  his.  For  I  am  deeply  convinced  that  in  this  matter 
there  is  no  question  of  right  and  wrong,  and  that  every  musical 
valuation  represents  no  more  than  an  accidental  judgment 
dependent  on  one's  own  nature,  entirely  ego-centric  and  thus 
objectively  of  no  account. 

Einstein  also  occupies  himself  in  an  active  sense  with 
music,  and  has  developed  into  a  very  fair  viohnist,  without 
claiming  higher  degrees  of  achievement.  Among  other  things 
I  once  heard  him  play  the  vioHn  part  of  a  Brahms  Sonata, 
and  his  performance  approached  concert  standard.  He  draws 
a  beautiful  tone,  infuses  expression  into  his  rendering,  and 
knows  how  to  overcome  the  technical  difficulties.     Among 


EINSTEIN'S  LIFE  AND  PERSONALITY        235 

the  supreme  artists  of  his  instrument  who  have  exerted  a 
personal  influence  on  him,  Joachim  assumes  the  first  place. 
Einstein  still  speaks  with  great  enthusiasm  of  Joachim's 
performance  of  Beethoven's  Tenth  Sonata  and  of  Bach's 
Chaconne.  He  himself  plays  the  latter  piece,  for  which  the 
purity  and  accuracy  of  his  double  and  multiple  stopping  fits 
him.  Whoever  chooses  the  right  moment — ^this  good  fortune 
has  not  yet  befallen  me — may  overhear  Einstein  at  his  pianistic 
studies.  As  he  confessed  to  me,  improvisation  on  the  piano  is 
a  necessity  of  his  fife.  Every  journey  that  takes  him  away 
from  the  instrument  for  some  time  excites  a  home-sickness  for 
his  piano,  and  when  he  returns  he  longingly  caresses  the  keys 
to  ease  himself  of  the  burden  of  the  tone  experiences  that  have 
mounted  up  in  him,  giving  them  utterance  in  improvisations. 

The  regular  run  of  concerts  in  which  displays  of  bravura 
play  an  important  part  finds  Uttle  favour  with  him  ;  above  all, 
he  is  not  a  worshipper  of  the  orchestral  conductor,  whom  he 
regards  only  as  an  interpreter  and  not  as  a  virtuoso  on  the 
orchestral  instrument .  He  expressed  this  idea  in  unmistakable 
words :  "  The  conductor  should  keep  himself  in  the  back- 
ground." I  believe  that  his  dearest  wish  would  be  to  breathe 
in  the  tones  without  a  personal  or  material  medium,  merely  out 
of  the  air  or  out  of  space.  Furthermore,  I  believe  that  there 
is  an  unfathomable  connexion  between  his  musical  instinct 
and  his  nature  as  a  research  scientist.  For  the  ear,  as  we 
know  from  Mach,  is  the  true  organ  that  enables  us  to  experience 
space,  and  thus  things  may  occur  within  the  ear  of  the  investi- 
gator of  space  that  may  have  a  different  significance  from 
that  of  music  which  is  represent  able  in  tones.  I  strongly 
doubt  whether  traces  of  compositional  form  occur  in  Einstein's 
tone-monologues,  but  perhaps  they  contain  examples  of  an 
art  for  which  the  aesthetics  of  a  distant  future  may  find  a 
name. 

With  regard  to  higher  literature,  and  indeed  all  writings 
not  connected  with  science,  Einstein  has  Uttle  to  say.  He 
himself  rarely  directs  conversation  on  to  this  topic,  and  still 
less  rarely  does  he  give  vent  to  an  enthusiastic  outburst  that 
betrays  warm  interest.  He  restricts  himself  to  making  short, 
aphoristic  comments,  and  now  and  then  allows  his  listener 


236  EINSTEIN  THE  SEARCHER 

to  gather  that  he  can  easily  imagine  an  existence  without 
literature.  The  number  of  accepted  novels,  tales,  and  poetic 
works  which  he  has  not  read  is  legion,  and  all  the  pretentiously 
artistic,  historical,  and  critical  writings  that  are  added  to  them 
have  attracted  only  a  very  momentary  interest  from  him. 

I  have  never  seen  him  attracted  in  any  way  by  the  pro- 
mising aspect  of  some  new  book  intended  for  diversion.  If 
such  a  one  happens  to  get  into  his  hands,  he  merely  places  it 
among  the  others.  At  times  I  was  constrained  to  think  of 
Caliph  Omar's  words  :  "  If  the  book  contains  what  is  already  in 
the  Koran,  it  is  unnecessary ;  if  it  contains  something  else,  it  is 
harmful."  It  is  harmful  at  least  in  the  sense  that  it  robs  us 
of  time  that  may  be  better  spent  in  another  way.  I  am 
purposely  exaggerating  here  to  make  it  quite  clear  that  Einstein 
finds  full  satisfaction  in  a  narrow  circle  of  literature,  and  that 
he  experiences  no  loss  if  numerous  new  works  pass  by  and 
escape  his  notice. 

Nevertheless,  he  speaks  with  reverence  of  a  series  of  authors, 
to  whom  he  owes  enrichment  :  among  them  are  the  classical 
writers,  who  naturally  occupy  the  highest  position,  with 
certain  exceptions,  which  he  equally  naturally  wishes  to  be 
taken  as  a  personal  opinion  and  not  in  the  sense  of  a  critical 
valuation.  With  him  the  difference  reveals  itself  in  the  in- 
tonation from  which  we  may  read  a  greater  or  lesser  measure 
of  affection.  When  he  says  **  Shakespeare,"  the  eternal 
greatness  seems  to  be  inherent  in  the  actual  sound  of  the 
name.  When  he  says  "  Goethe,"  we  notice  a  slight  undertone 
of  dissonance,  which  may  be  interpreted  without  difficulty. 
He  admires  him  with  the  pathos  of  distance,  but  no  warmth 
glows  through  this  pathos. 

I  had  ventured  to  deduce  from  my  knowledge  of  his  nature 
the  men  and  the  works  which,  in  my  opinion,  should  awaken 
strong  echoes  in  him.  A  fairly  clearly  defined  line  leads  to 
the  true  path.  Outside  of  any  systematic  series,  I  may 
mention  Dostojewski,  Cervantes,  Homer,  Strindberg,  Gottfried 
KeUer  in  the  positive  sense,  Emile  Zola  and  Ibsen  in  the 
negative  sense.  Taken  as  a  whole,  this  prognostication  does 
not  disagree  seriously  with  his  own  statement,  excepting 
that  he  lays  still  greater  emphasis  on  Don  Quixote  and  the 
Brothers  Karamasoff  than  I  had  surmised.     He  expressed 


EINSTEIN'S  LIFE  AND  PERSONALITY        237 

himself  with  reserve  about  Voltaire.  He  has  no  belief  in 
Voltaire's  poetic  qualities,  and  sees  in  him  only  a  subtle- 
minded  and  amusing  writer.  Perhaps  if  Einstein  were  to 
devote  himself  a  little  more  intensively  to  Voltaire  and  Zola, 
he  would  assign  a  higher  value  to  these  related  spirits.  But 
there  is  little  hope  of  this  occurring,  as  the  wide  range  of 
Voltaire's  works  tends  to  restrain  him.  Time,  which  the 
physicist  Einstein  has  shown  to  be  relative,  has  an  absolute 
value  for  him  when  measured  in  hours,  and  whoever  seeks  to 
persuade  him  to  read  thick  volumes  is  not  Ukely  to  gain  his 
goodwill. 

Our  philosophical  Uterature  is  not  received  with  acclama- 
tion by  him.  If  some  one  wished  to  undertake  the  task  of 
ascertaining  Einstein's  attitude  towards  philosophy,  he  would 
be  well  advised  to  plunge  into  Einstein's  works  rather  than  to 
ask  him  personally.  In  them  the  questioner  would  find  ample 
hints,  pointing  towards  a  new  theory  of  knowledge,  the  first 
indications  of  which  are  already  perceptible.  A  great  portion 
of  philosophic  doctrine  will  yet  have  to  pass  through  the 
Einstein  filter  to  be  purified.  He  himself,  it  seems  to  me, 
leaves  this  process  of  filtering  mostly  to  other  thinkers,  but  we 
must  not  lose  sight  of  the  fact  that  these  others  derive  their 
views  of  space,  time,  and  causality  from  Einstein's  physics. 
It  is  thus  immediately  evident  that  he  does  not  find  revelations 
about  ultimate  things  in  already  extant  Uterature,  for  the 
simple  reason  that  they  are  not  to  be  found  there.  For  him 
famous  works  represent,  in  Kant's  language,  "  Prolegomena 
to  every  future  system  of  metaphysics  which  can  claim  to 
rank  as  a  science."  The  accent  is  to  be  put  on  the  future 
that  has  not  yet  become  the  present.  He  praises  many, 
particularly  Locke  and  Hume,  but  will  grant  finality  to  none, 
not  even  to  the  great  Kant,  not  to  mention  Hegel,  Schelling, 
and  Fichte,  whom  he  barely  mentions  in  this  connexion. 
To  Schopenhauer  and  Nietzsche  he  assigns  a  high  position  as 
writers,  as  masters  of  language  and  moulders  of  impressive 
thoughts.  He  values  them  for  their  Hterary  excellence,  but 
denies  them  philosophic  depth.  As  far  as  Nietzsche  is  con- 
cerned, whom,  by  the  way,  he  regards  as  too  gUttering,  Einstein 
certainly  experiences  ethical  objections  against  this  prophet  of 
the  aristocratic  cult  whose  views  are  so  diametrically  opposed 


238  EINSTEIN  THE  SEARCHER 

to  Einstein's  own  opinion  of  the  relations  between  man  and 
man. 

Earlier  when  we  were  talking  of  classical  poetry  he  had 
particularly  emphasized  Sophocles  as  one  who  was  dear  to  him. 
And  this  name  leads  us  to  the  innermost  source  of  Einstein  as 
a  man.  "  I  am  not  here  to  hate  with  you  but  to  love  with 
you/'  is  the  cry  of  Sophocles'  Antigone,  and  this  cry  is  the  key- 
note of  Einstein's  emotional  existence.  I  shall  not  give  way 
to  the  temptation  to  follow  those  who  in  the  turmoil  of  the 
present  day  refer  to  Einstein  as  a  political  figure.  That  would 
lead  to  a  description  of  policy  and  party  arguments  that  lie 
beyond  the  scope  of  this  book  ;  so  much  the  less  am  I  incHned 
to  do  so  as  Einstein's  convictions  may  be  expressed  very  clearly 
without  reference  to  schematic  terms  of  a  very  elastic  nature. 
An  individuality  such  as  his  cannot  be  compressed  into  a  party 
programme .  And  if  anyone  should  insist  on  placing  him  among 
the  radicals  or  on  assigning  him  far  to  the  left,  I  should  suggest 
that  it  would  be  better  to  choose,  instead  of  the  classification 
right  and  left,  that  of  above  and  below.  I  look  up  towards  his 
idealism,  whose  altitude  may  perhaps  be  reached  one  day  by 
the  raising  of  our  ethical  standards.  But  not  by  means  of 
paragraphs  of  laws.  I  have  seldom  heard  him  talk  of  such 
schematic  recipes,  but  so  much  the  nftore  have  I  noted  utter- 
ances which  bore  witness  to  a  very  intense  and  ever-present 
sympathy  with  every  human  creature.  His  programme,  which 
is  written  not  in  ink  but  in  heart 's-blood,  proclaims  in  the 
simplest  manner  the  categorical  imperative  :  Fulfil  your  duty 
to  your  fellow-being  :  offer  help  to  every  one  :  ward  off  every 
material  oppression.  "  Well,  then,  he  is  a  socialist,"  so  the  cry 
runs.  If  it  is  your  pleasure  to  call  him  so,  he  will  not  deny  you 
it.  But  to  me  this  term  seems  to  denote  too  narrow  limits  for 
him.  I  see  no  contradiction  in  applying  the  term,  but  there  is 
no  perfect  congruence.  If  one  word  is  necessary,  I  should  be 
rather  more  inclined  to  say  that  he  is  in  the  widest  sense  a 
democrat  of  liberal  trend. 

For  him  the  State  is  not  its  own  aim,  nor  does  he  imagine 
himself  to  be  the  possessor  of  a  panacea.  "  The  attitude  of  the 
individual  to  socialism,"  he  said,  "  is  uncertain  owing  to  the 
fact  that  we  can  never  ascertain  clearly  how  much  of  the  iron 
compulsion  and  blind  working  of  our  economic  system  may  be 


EINSTEIN'S  LIFE  AND  PERSONALITY        289 

overcome  by  appropriate  institutions."  And  I  should  like  to 
add  that  such  instituj:ions  would  scarcely  have  a  permanent 
result,  but  that  more  may  be  expected  from  the  ethical  example 
of  those  who  have  the  power  of  renunciation.  Whoever 
reaUzes  the  motto  of  Antigone,  "  I  am  here  to  love  with  you," 
brings  us  nearer  the  goal.  All  in  all,  our  longing  continually 
flees  from  the  confusion  of  poUtical  considerations  to  simple 
morality.  For  Einstein  this  is  the  primary  element,  that 
which  is  directly  evident  and  not  open  to  misrepresentation. 
It  includes  sympathy,  and,  what  is  more  important,  joy  in 
conjunction  with  others.  "  The  best  that  hfe  has  to  offer," 
he  once  exclaimed,  **  is  a  face  glowing  with  happiness  !  " 

This  look  is  expressed  on  his  own  face  when  he  discusses 
his  ideals,  above  all  the  internationahty  of  all  intellectual 
workers  and  the  reaUzation  of  eternal  peace  among  the  nations. 
To  him  pacifism  is  a  matter  of  mind  as  weU  as  of  heart,  and  he 
is  of  the  opinion  that  the  course  of  history  so  far  is  but  the 
prelude  to  its  reaUzation.  The  past,  with  its  bloodstained 
fingers  that  reach  into  the  present,  does  not  discourage  him 
He  points  to  the  endless  city  wars  of  the  Middle  Ages  in  Italy, 
which  had  finally  to  cease  in  answer  to  the  increasing  feeling 
of  solidarity.  So  he  believes  in  the  victory  of  peace,  which 
the  unified  consciousness  of  all  humanity  will  one  day  win  over 
the  demonic  powers  of  tyranny  and  conquest. 

The  pacifist ic  goal  seems  to  him  to  be  attainable  without  the 
peculiarities  of  the  various  States  being  destroyed.  National 
characteristics  arising  from  tradition  and  hereditary  influences 
do  not  signify  in  his  eyes  a  contradiction  to  the  internationalism 
that  embraces  the  common  intellectual  factors  of  civilized 
peoples.  Thus  the  desire  for  the  preservation  and  care  of 
particularities  directs  him  to  the  secondary  goal  of  Zionism. 
His  blood  asserts  itself  when  he  supports  the  foundation  of  a 
State  in  Palestine,  which  seems  to  him  to  be  the  only  means  of 
preserving  the  national  individuaUty  of  his  race  without  the 
freedom  of  the  individual  being  affected. 

We  had  left  Art  to  talk  of  the  State,  and  then  returned  to 
the  former  theme  to  touch  lightly  on  the  pictorial  arts.  Paint- 
ing was  allowed  to  pass  with  merely  a  fleeting  remark.  It 
plays  no  considerable  part  in  Einstein's  existence,  and  he 
would  not  suffer  great  grief  if  it  were  to  vanish  from  the  plane 


240  EINSTEIN  THE  SEARCHER 

of  culture,  a  consummation  to  which  definite  signs  seems  to 
point.  I  have  described  these  signs  in  other  writings  (as  in 
Kunst  in  looo  Jahren),  and  maintain  the  point  of  view  that  the 
latest  branches  of  painting  as  represented  by  expressionism  and 
cubistic  futurism  denote,  in  essence,  the  last  convulsions  of  a 
dying  surface  art .  And  even  the  chief  represent  ati ves  of  former 
flourishing  periods  are  beginning  to  fade  away,  and  Einstein  will 
not  be  the  only  one  who  will  relegate  this  art,  as  compared  with 
music,  to  a  lower  plane  among  the  inspired  arts  that  bring  joy 
to  humanity.  He  is  only  more  frank  than  others  when  he 
freely  confesses  that  he  cannot  convince  himself  that  a  life 
without  the  joys  of  pictorial  art  would  be  hopelessly  impover- 
ished. But  he  bows  his  head  to  sculpture,  and,  for  him, 
architecture  is  a  goddess.  It  is  again  his  deeply  rooted  piety 
that  asserts  itself  when  memory  recalls  to  him  the  Gothic  dome 
with  its  pinnacles  striving  towards  heaven.  Goethe  and 
Schlegel  have  called  architecture  "  frozen  music,"  and  this 
picture  is  present  in  his  mind  when  he  sees  Gothic  architecture 
as  frozen  music  of  Bach.  It  is  open  to  anyone  to  analyse  this 
specific  impression  in  another  way  by  seeking  the  fundamental 
elements,  in  which  the  essence  of  the  art  is  to  provide  support 
for  a  weighty  structure  and  to  overcome  gravitation.  For  a 
spirit  that  works  with  mechanics  and  that  feels  within  itself  the 
pressures  and  tensions  occurring  in  external  nature,  archi- 
tecture is  a  kind  of  statics  and  dynamics  transformed  into  a 
thing  of  beauty,  a  ravishing  picture  of  his  own  science. 

Einstein  has  told  me  many  a  story  of  his  travels,  and 
these  reports  were  characterized  by  an  absence  of  definite 
purpose.  The  conception  of  something  worth  seeing  in  the 
tourists'  sense  does  not  exist  for  him,  and  he  does  not  set  out  in 
eager  pursuit  of  those  things  that  are  marked  with  two  asterisks 
in  Baedeker.  The  intense  romanticism  of  Swiss  scenery,  that 
lay  within  such  easy  reach  for  him,  has  never  enticed  him  into 
its  magic  circle,  and  he  has  nothing  to  do  with  the  abysmal 
terrors  of  glaciers  and  the  world  of  snow-peaks.  His  en- 
thusiasm for  landscape  beauty  conforms  with  the  behaviour  of 
the  barometer  :  the  greater  the  altitude,  the  lower  the  mercury. 
In  simple  contact  with  Nature  he  prefers  the  lesser  mountains, 
the  seashore,  and  extensive  plains,  whereas  brilliant  panoramic 


EINSTEIN'S  LIFE  AND  PERSONALITY        241 

contours  like  those  of  the  Vierwaldstetter  See  do  not  rouse 
him  into  ecstasy.  It  is  unnecessary  to  remark  that  he  does 
not  arrange  his  Uving  on  the  standard  of  the  Grand  Palace 
Hotels  en  route.  It  is  nearer  the  truth  to  picture  him  as  a 
vagrant  who  tramps  along  without  a  sense  of  time  and  without 
a  goal,  in  the  fairy  atmosphere  of  a  joyous  wanderer  who  has 
unconsciously  adopted  the  old  rule  of  Philander  :  Walk  with 
a  steady  step  :  make  your  burden  small :  start  early  in  the 
morn,  and  leave  home  all  care  ! 

Am  I  to  record  the  Hst  of  pleasures  and  hobbies  that  are 
foreign  to  him  ?  The  Ust  would  be  very  long,  and  I  should 
arrive  at  my  goal  more  quickly  by  setting  his  sporting  tendencies 
equal  to  zero.  I  once  suspected  him  of  being  given  to  aquatic 
sport,  as  I  learned  that  he  had  taken  part  in  several  yachting 
excursions.  But  I  was  mistaken.  He  sails  in  the  same  way 
as  he  walks  on  his  tours,  without  a  set  purpose,  dreaming,  and 
uninterested  in  what  is  regarded  by  members  of  sailing  clubs 
as  a  "  feat/*  In  the  negative  list  of  his  games  we  see  even 
chess,  that  usually  exerts  a  strong  attraction  on  natures  with 
a  mathematical  tendency.  The  particular  types  of  combina- 
tion offered  by  this  game  have  never  tempted  him,  and  the 
world  of  chess  has  remained  terra  incognita  for  him.  He  is 
just  as  little  interested  in  every  kind  of  collection,  even  that  of 
books.  I  have  seldom  or  never  met  a  savant  who  attaches  so 
little  value  to  the  personal  possession  of  numerous  and  valuable 
books.  This  statement  may  be  extended  as  far  as  saying  that 
he  experiences  no  pleasure  at  all  in  possession  as  such  :  he 
says  so  himself,  and  his  whole  manner  of  Ufe  proves  it.  There 
seems  to  me  to  be  an  element  of  resignation  in  his  amiable 
hedonism,  a  kind  of  monkish  asceticism.  He  never  rids  him- 
self of  the  feeling  that  he  is  only  paying  a  visit  in  this  world. 

I  do  not  know  whether  Einstein  considers  that  his  life- 
work  can  be  completed  within  the  span  of  this  visit.  At 
any  rate  he  makes  no  attempt  to  extract  more  out  of  the  day 
by  following  a  rigid  programme  of  work  than  the  day  volun- 
tarily offers.  He  does  not  compel  himself  to  cover  a  definitely 
circumscribed  piece  of  ground  with  chronological  exactitude. 
There  are  brain-workers,  especially  artists,  who  actually  never 
shake  off  the  fetters  of  the  twenty-four  hours  day  of  work 
inasmuch  as  they  spin  on  the  threads  of  daily  effort  into  the 
i6 


242  EINSTEIN  THE  SEARCHER 

nightly  fabric  of  dreams.  Einstein  can  make  a  pause,  inter- 
rupt liis  work,  or  divert  himself  into  side-channels  at  leisure 
and  according  to  the  demands  of  the  hour,  but  dreams  offer 
him  no  inspiration  and  do  not  waylay  him  with  problems. 

On  the  other  hand,  however,  he  is  waylaid  so  much  the 
more  during  the  day  by  things  and  persons  that  make  an 
assault  on  him.  This  starts  as  soon  as  the  first  post  arrives, 
to  see  through  which  requires  a  special  bureau.  In  addition 
to  the  communications  of  a  professional  or  official  nature 
there  appear  innumerable  letters  from  everywhere  and  any- 
where asking  him  to  grant  a  little  of  his  time.  Whatever 
each  individual  writer  has  thought  about  the  principle  of 
relativity,  all  his  thoughts  and  doubts,  additions,  and,  above 
all,  that  which  he  has  not  been  able  to  understand,  all  this  is 
to  be  answered  by  Einstein.  Has  he,  the  child  of  fame,  even  a 
quarter  of  an  hour  for  himself  ?  There  they  wait  in  the  hall, 
the  painter,  the  photographer,  the  sculptor,  and  the  inter- 
viewer ;  with  whatever  powers  of  persuasion  and  argumenta- 
tive subtlety  his  attentive  wife  may  seek  to  defend  his  hours 
of  rest,  some  of  these  visitors  will  yet  succeed  in  gaining  the 
upper  hand,  and  will  produce  something  in  oil-colours,  in 
plaster  of  Paris,  in  black  and  white,  in  water-colours,  or  in 
print.  Fame,  too,  demands  her  sacrifices,  and  if  we  talk  of  a 
hunt  after  fame,  then  Einstein  is  certainly  not  the  hunter, 
but  the  hunted. 

He  sighs  under  the  burden  of  his  correspondence,  not  only 
as  the  recipient,  but  also  with  the  sender,  whose  letter  has  to 
remain  unanswered.  Yet  he  is  never  roused  to  anger  by  the 
intruder  on  his  time.  If  this  were  not  so,  the  aphorism  of 
Cyrus  that  patience  is  the  panacea  of  all  ills  would  not  hold 
for  him,  and  how  would  I  myself  otherwise  have  dared  to 
claim  so  many  hours  of  him  ?     A  sense  of  guilt  falls  on  me  ! 

But  even  Einstein's  patience  can  come  to  an  end,  and  this 
is  at  the  point  where  "  society  "  begins  :  I  mean  the  con- 
gregation of  persons  in  a  salon,  society  entertainments  to 
which  one  is  invited  to  be  seen,  and  so  that  one  may  claim 
to  have  been  there.  A  solemn  representation  in  which  he  is 
to  be  made  the  cynosure  of  all  eyes  is  a  torture  to  him.  If  in  a 
very  exceptional  case  he  is  compelled  to  participate  in  such  a 
gathering,  the  joy  of  his  hosts  will  not  be  entirely  unmixed. 


EINSTEIN'S  LIFE  AND  PERSONALITY        243 

for  it  does  not  require  a  thought -reader  to  recognize  the  longing 
for  solitude  imprinted  on  his  countenance  :  "  Could  I  but 
escape  !  " 

So  much  the  happier  does  he  feel  himself  in  the  narrow 
circle  of  his  friends,  who  offer  what  means  tp  him  much  more 
than  admiration,  namely,  affection,  and  an  appreciation  of 
his  human  self.  He  is  what  one  wishes  him  to  be.  He  is 
happy  when  he  can  forget  the  doctor  profundus,  and  can 
yield  himself  up  to  the  atmosphere  of  stimulating  and  un- 
constrained converse.  He  is  a  master  in  the  art  of  Hstening, 
and  is  not  averse  to  contradiction  ;  when  possible,  he  even 
emphasizes  the  arguments  of  his  opponent.  Audiatur  et 
altera  pars  !  This  is  a  further  manifestation  of  his  altruistic 
personality,  which  rejoices  when  he  extracts  the  true  kernel 
from  the  husk  of  the  opposing  opinion.  Here  he  also  displays 
a  characteristic  which  one  does  not  usually  expect  to  find  among 
abstract  thinkers,  a  sense  of  humour  that  runs  through  the 
whole  gamut  from  a  gentle  smile  to  hearty  laughter,  and  that 
is  the  happy  source  of  many  a  striking  sally.  It  may  happen 
that  the  subject  of  conversation  excites  his  anger,  especially 
in  political  debates  when  he  calls  to  mind  militaristic  or  feudal 
misgovernment.  He  then  becomes  roused,  and,  as  a  cynical 
philosopher,  sarcastically  attacks  personaHties  and  points  out 
the  primary  source  of  perennial  hate,  immediately  afterwards 
soaring  up  to  happy  speculations  of  the  future. 

It  is  a  matter  for  regret  that  the  subjects  that  he  has 
discoursed  on  lightly  have  not  been  fixed  phonographically. 
Such  records  would  form  an  interesting  supplement  to  the 
conversations  outhned  in  this  book.  It  would  never  occur 
to  him  to  set  down  in  permanent  literary  form  the  inspiration 
of  the  moment.  What  he  writes  emanates  from  other  regions, 
and  is,  to  use  his  own  expression,  a  precipitate  of  **  thick  ink.'* 
This  is  obvious,  for  what  he  has  to  proclaim  as  a  scientist 
cannot  be  presented  in  a  "  thin  "  form.  But  many  a  so-called 
writer  would  have  reason  to  congratulate  himself,  if  so  much 
thinly  flowing  matter  occurred  to  him  in  writing  as  to  Einstein 
in  speaking. 

The  record  of  these  conversations  was  began  in  the  summer  of  1919,  and 
completed  in  the  autumn  of  1920. 


INDEX 


Aristoteles,  41 
Arrhenius,  144 

Babinet,  25 
Bach,  88,  235 
Bacon,  46 

Baer,  K.  E.  von,  162 
Bailhaud,  144 
Beethoven,  99,  234,  235 
Bell,  Graham,  25,  iii 
Beranger,  84 
Bergson,  91 
Bernoulli,  48 
Bernstein,  225 
Bessel,  32 

Bohr,  Niels,  57,  210 
Brahe,  Tycho,  94 
Bruno,  Giordano,  141 
Biichner,  225 
Bulwer,  76 
Bunsen,  164 
Byron,  9 

Cantor,  52,  203 
Cavendish,  iii 
Ceulen,  Ludolf  van,  158 
Condillac,  216 
Copernicus,  6,  90 
Cosmati,  48 

Curie,  Madame,  79,  231 
Cuvier,  196 

Darboux,  152 
Dase,  158 

Descartes,  47,  133,  162 
Dingeldey,  190 
Dostojewski,  185,  187 
Dove,  21,  155 
Duhem,  105,  106 
Duhring,  54,  56 

Eckermann,  50,  85 
Edison,  140 
Euclid,  180 
Euler,  98 
Euripides,  85 

Faraday,  39,  61,  84 
Fechner,  no,  182 


Fermat,  97,  190 
Fizeau,  113 
Flammarion,  115 
Franklin,  102 
Fresnel,  45 

Galilei,  6,  40,  150,  179,  181 

GaUe,  6 

Galvani,  no 

Gauss,  55,  185,  186 

Goethe,   13,  23,  179,   197,  212,  236 

240 
Grillparzer,  95 
Grossmann,  229 

Hansen,  134 

Hebbel,  77,  86 

Hegel,  42 

Heine,  49 

Helmholtz,  25,  26,  53,  73 

Heraclitus,  23 

Herschel,  84 

Hertz,  60 

Hooke,  41 

Horace,  3 

Humboldt,  49 

Hume,  161 

Huyghens,  56,  109,  132 

Jean  Paul,  86,  223 

Joule,  84 

Jung  Stilling,  84 

Kant,  35,  121,  170,  177,  179,  237 
Kepler,  6,  42,  84,  176,  177 
Kirchhofif,  104-7,  148,  212 
Kleist,  130 
Kummer,  190 

Lamarck,  197 

Lange,  47 

Laplace,  40,  45,  140,  165 

Leibniz,  26,  128 

Leonardo  da  Vinci,  11,  50-54 

Leverrier,  6,  10 

Liebig,  55 

Lindemann,  158 

Linn6,  196 

Lorentz,  57,  72 


a45 


246 


EINSTEIN  THE  SEARCHER 


Lothar  Meyer,  107 
Lucretius,  210 

Mach,  46,  77,  108,  149,  169 
Mauthner,  95 
Maxwell,  39,  60 
Mayer,  Robert,  25,  55,  56 
Melanchthon,  82 
Menander,  86 
Mendelejew,  107 
Mezzofanti,  63 
Michelangelo,  49 
Michelson  and  Morley,  112 
Mill,  45 

Mithridates,  63 
Montaigne,  77 
Mozart,  233 

Newton,  2,  6,  8,  39,  40,  43,  96 
Nietzsche,  63,  217,  237 
NoUet,  103 

Odilon,  Helene,  135 
Oersted,  109 
Ostwald,  83,  231,  232 
Ovid,  197 

Pascal,  93,  98 

Pasteur,  175 

Perrin,  154 

Pfliiger,  35 

Philander,  241 

Picard,  144 

Planck,  57,  59,  91,  230 

Poincare,  i,  7,  112,  116,  231 

Pope,  54 

Priestley,  iii 

Psellus,  156 

Pyxrhon,  92 

Pythagoras,  loi,  179 


Quetelet,  182 

Regiomantus,  52 
Reis,  25 
Riemann,  186 
Riggenbach,  25 
Ruess,  224 
Rutherford,  36,  210 

Schiller,  74,  94,  170 
Schlegel,  240 
Schlick,  Moritz,  168 
Schopenhauer,  41,  237 
Schwann,  175 
Shakespeare,  236 
Siemens,  25,  27-30 
Slade,  136 
Sophocles,  238 
Spinoza,  84,  162 
Stephenson,  25 

Terence,  191 
Thomas  Aquinas,  165 
TorriceUi,  166 

Vaihinger,  45,  169 
Vitruvius,  loi 
Volta,  no,  III 
Voltaire,  47,  237 

Wagner,  234 
Weber,  182 
Weierstrass,  152 
Weyl,  34 
Whewell,  45 
Wien,  173 

Zelter,  84 
Zollner,  137 


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MORRISON   AND  GIBB   LIMITED 

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UNIVERSITY  OF  CALIFORNIA  LIBRARY 
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